Recent Posts by the IRIS Interns http://www.iris.edu/internship/blogs 2012-11-20T19:05:31-05:00 IRIS Internship http://www.iris.edu/hq/internship/rss/interns/field_work_photos

John Hole has put together a website with photos of field work. It also includes an overview of the proposal.   http://www.geophys.geos.vt.edu/hole/idor/

2012-11-20T19:05:31-05:00 http://www.iris.edu/hq/internship/rss/interns/final_blog1

I feel that my summer was a success, but not for the reasons that I thought it would be. Listed below are the goals that I wrote on the back of the project summary page at the beginning of the summer. First third of the internship:      1. learn to use all the programs to a level where I am proficient      2. mingle with the scientific community and make professional connections      3. Gain a full understanding of the goals and logistics of my project During the first portion of the summer I learned to use a program called SeisSpace to pick arrival times for shot gather data from the Salton project. It was a good experience learning to use the program, because more than learning the specific program, I gained more experience picking the first arrival times of seismic waves within noise. It was good to be able to work with real data. As for the mingling with the scientific community I didn’t get to meet a lot of people in the first portion of my internship. I mostly met graduate students attending Virginia Tech. I read through the scientific proposal for the project and talked with Kathy Davenport, the PHD student in charge of IDOR. I gained a thorough understanding of the goals of the internship by reading this paper and discussing it, but it took going to the field for the first time to fully understand the logistics of the project. Second third of the internship:      1. Have a clear visual idea of our survey area.      2. be confident and comfortable with directing others During the middle of the internship we traveled to Idaho to survey the area of our study. While we were in Idaho I poured over route information to better understand where we are going. During the second trip, when we were completing the field work I created and scanned maps of the field area that were used to guide the deployers. Through these activities I gained a comprehensive knowledge of the study area. Traveling from town to town and surveying the line helped me gain a first hand knowledge of the area. During the last bit of the internship, while in Idaho, I met the deployers at the door, checked them into their rooms and introduced myself. While I was there I felt like the deployers looked up to me and called me to help sort out problems. Third third of the internship:      1. be physically fit enough for field work      2. write my abstract (and by proud of it) During the last part of the internship we spent three days deploying the instruments. This required digging the holes with a pickax, placing the Texan at one end and securely placing the geophone in the other. After this we buried the entire thing. I was physically fit enough to do the work, which makes me feel proud. I also finished my abstract, and feel proud of it. I feel that my summer was a success because I learned a lot and felt like I gained a lot of independence. I feel more confident about my future now and more confident about making connections and looking for a graduate school for the coming year.  

2012-09-03T22:03:22-05:00 http://www.iris.edu/hq/internship/rss/interns/final_blog

My experience as an IRIS Intern this past summer was more exciting and beneficial than I could have ever imagined. I achieved many of the summer goals I set for myself and some of my long term goals as well. The following is the progress I made on the goals I mentioned in my first blog. • Explore all the different areas in Geophysics. I now have expanded my knowledge of the field. Not only did I learn many things through talks with my host professor, but I took the time to meet with other professors as well. I met with a geomorphologist at Virginia Tech to learn more about his research. I also took advantage of the time I spent with all the different professors during IDOR. I learned about things like passive source seismology and all the different methods of near surface geophysics. • Gain a better understanding of what area of Geophysics I might want to pursue in graduate school. After learning about all the different areas of Geophysics, I am most interested in near surface geophysics. Knowing this I am continuing to expand my understanding of this area in order to decide exactly what I will pursue. • Learn how to make a professional scientific poster. Due to my limited time working on SSIP, I only had enough time to finish my data processing before I had to leave for IDOR. Therefore, I did not have time to start a poster. This semester I will be taking a couple of workshops on poster presentations to help reach this goal. • Become familiar with a variety of computer programs and software used in Geophysics research. This summer I definitely became familiar with several different types of software. The two I became most familiar with were MatLab and SeisSpace. • Expand my knowledge of writing code and understanding scripts. I wish I would have had more time to spend with writing code this summer. I did spend quite a bit of times learning how to read the scripts I was using to run my tomography model and modifying them slightly. I look forward to my next coding opportunity. • Be able to branch out and explore new places and new cultures and meet new people while doing this. I went to several town festival while in Blacksburg, VA and even had the chance to hop on a bus to Christiansburg, VA and explore the town. I met a great group of people in Virginia and met even more during my time in Idaho. My experience overall was more than I could have ever asked for. I ended my experience off on a high note. After proposing IDOR Gives Back, which was an idea to donate all the unwanted blankets and pillows used during IDOR, I got to deliver all the items to a shelter in Boise, ID on my way to the airport. Now that it is over, I can't wait to continue finalizing my presentation for the AGU Fall Meeting. I am so grateful to have been an IRIS Intern. This summer I not only grew as a student and researcher, but as a person as well. Goodbye, Sincerely, Amanda  

2012-09-02T18:14:17-05:00 http://www.iris.edu/hq/internship/rss/interns/summary_of_a_splendid_summer

Hunkering down for Isaac at Tulane University, I am finally realizing that my amazing summer of research is over. I have been able to learn so much from this summer. With the help of my wonderfully patient IRIS hosts, I have been able to grasp concepts that I thought would be impossible to learn after the first week in New Mexico. Becoming comfortable with both looking to papers for answers and learning something I had never heard of before is something I will be able to take with me into grad school or any job I choose to have after college. I was especially appreciative of the internship because there is no geophysicist at Tulane and so I had never seriously been introduced to seismology. Because I enjoyed the internship so much, I plan to continue to do research in the same area through an independent study here at Tulane. I will continue my project by calculating synthetic receiver functions to further investigate a change in the amplitude ratio of the LAB to the Moho over different frequency ranges and then analyzing receiver functions for different geologic settings (Craton, orogenic belt, rift, ocean island). I am very lucky to have such supportive hosts that will help me throughout the semester. Along with continuing the project this next semester, I will be applying to grad school for seismology. I would have never found that I enjoyed seismology so much had it not been for the IRIS internship and I am excited to see everyone in December at AGU!  

2012-08-27T20:34:40-05:00 http://www.iris.edu/hq/internship/rss/interns/week_9_and_week_10

Week 9 consisted of going out and picking up all the seismometers we deployed the previous week. It seemed like a giant treasure. For three straight days we went out with GPS in hand to locate the sights of the seismometers. We had to locate the exact burial location a the sights by searching for clues such as a mound of dirt, an out of place rock, or an oddly positioned twig. Then in an attempt to not damage the equipment we dug up the seismometers by hand. We then shined up our newly found treasure and put it in our treasure chest as shown below. The photo above shows Texans laying in a protective case after pick-up. All the deployed instruments made it back from the field. None were lost or taken by the wildfires on the east end of the line near Stanley, Idaho. All the volunteers also made it back from the field in good spirits. Many with fun stories to tell about their adventures. My fun story took place on the second day of pick-up. My partner for the day was Dr. Ray Russo from the University of Florida. He and his crew have over 80 operating broadband stations throughout Idaho as part of IDOR. I was lucky enough to visit two stations with him that day. After deploying a similar station during the IRIS Intern Orientation in New Mexico, I was thrilled to visit one in the field. The photo above shows a broadband station near Midvale, Idaho. The last few days of IDOR were spent washing all the dirt off the insides and outsides of the 20 plus vehicles and cleaning up the remaining equipment.  I thoroughly enjoyed my time working on IDOR and I am excited to see the final products of the project. Stay tuned for my final blog. Goodbye for now. Sincerely, Amanda

2012-08-27T08:24:58-05:00 http://www.iris.edu/hq/internship/rss/interns/week_12_-_the_end

August 20 to August 24 Last weekend I went with Marija to Questacon, the science center here. It was so much fun! We stayed until they kicked us out because it was closing. We had lots of fun with optical illusions and puzzles and simple machines and even a giant slide that had a small vertical section that allowed us to be in free fall for a very short time. Here’s a picture of me in a kaleidoscope! This weekend I’ll sleep in, do my laundry, and finish packing on Saturday, and then leave for home Sunday morning! I’m so excited to finally be heading home! But I’m also really going to miss everyone here. We had a goodbye dinner together with other people from the Earth Physics group for Gerry (who leaves on Tuesday) and me today, which was really nice. My adviser has been really fantastic and especially great at organizing events like the dinner which are fun and good for trying new things and meeting new people. I finished my work this week, we chose a checkerboard resolution and I plotted our tomography results and Yoshizawa’s tomography maps on the same color scale for comparison. It was good to see that we see consistently lower velocities for my values than Yoshizawa found both for the tomography results and the dispersion results. It would have been bad if the dispersion had all been lower velocity and the tomography had all been higher velocity. I can’t say anything too quantitative about the velocities I found but I can say that they are consistently lower velocities than the longer path solutions found by Yoshizawa and Kennett. It’s possible that this is an effect of using paths only within the continent, or that it is an effect of the receivers, or the particular way in which Yoshizawa and Kennett processed their data. It is exciting that I got a consistent result though! I have started working on my poster and I have most of the figures and text already I think but there will be many visual things to play with and lots of formatting and editing to do before AGU. I will also present a poster at my school summer research poster conference in early September so I need to finish up the working draft by then and then I’ll update it before December. This internship has really been a phenomenal experience for me, I’ve learned so much! And I actually managed to finish a project in this short time which was a major accomplishment. I think the thing I am most proud of is how much I learned about working in a Linux/Unix environment, coding and GMT. I have really enjoyed learning these very valuable skills and I’m sure I will use them a lot in the future. Thanks for a great summer IRIS and ANU! 

2012-08-24T07:29:38-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_version_eleven

The 11th and final version of the goals – I need to get these done by Friday!! • Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o Choose a resolution for the checkerboard test, I’ve checked a whole bunch but I haven’t really found anything I’m satisfied with yet. • Be able to produce a poster which describes my project that is up to professional standards for AGU o Gather all figures and write text for poster o Make a preliminary poster on illustrator! I think this about sums up what I have left to do! I’m also working on plotting Yoshizawa’s tomography maps on the same size and colorscale for comparison. Once I have a checkerboard resolution I’m satisfied with then we can compare those results and see if the comparison between the tomography maps and the dispersion curves yield a similar result. I finished gathering, processing and plotting data from an event that Yoshizawa used to create his dispersion curves and found that my resulting velocities were almost always within the standard deviation of his velocity values, which is an excellent indication that the deviations we see in the rest of my results may actually be due to the difference between using long and short wave paths. Here is one of the figures used for comparison from the event Yoshizawa used. And here is one of my checkerboard tests. The top figure is my tomography results. The bottom left is the input checkerboard model and the bottom right is the resulting inversion from the checkerboard model, which you can see is an okay approximation of the checkerboard but not excellent. Tomorrow morning we will decide on an appropriate resolution and then compare that to Yoshizawa’s tomography maps. I’m currently having a bit of trouble plotting them but I think I just have the latitude and longitude switched. I will also have a lot of cleaning up to do for the tomography plots, right now they’re just a very rough version to help us choose the right resolution. Anyways, cheers to a great internship and I really feel I’m quite close to finishing up, I hope I do actually finish this project in the next three days! I’ve really enjoyed my time here and my adviser has been really great to work with! This summer (winter) has been really great and I’ve learned a lot, especially about things I knew nothing about such as coding and keeping a blog! I’ll make a final post on Friday about the results, bye for now! 

2012-08-21T03:21:50-05:00 http://www.iris.edu/hq/internship/rss/interns/field_work_overview

haven't had a spare second to post for a while!  I am excited to announce that we have completed the field work with much success! We placed almost all of the texans (with some skipped due to equipment shortages and fire closures). We deployed instruments for three days, and I worked on the western half of the line while a team of deployers traveled east to Stanley, ID.  Then we got to have some fun on a geology based field trip while the shooting crew took care of their part of the job. The Texans and geophones (data collectors) picked up the energy. At this point we were able to pick the instruments back up from the sites. This time I was sent with the Stanley crew to work on pickup. There are some quite large and uncontrolled fires in Idaho currently that at this time had grown quite large and filled the air in the town with smoke, making it important to keep people with breathing problems in Ontario, OR.   Being on the eastern end I got to work in the mountains and saw some amazing views. Picking up the texans was faster going than deploying them, so I spent the last day with our friends at Les Schwab getting all the tires fixed from the cars.  All in all, being here was a wonderful experience. I learned a lot (which will be reflected on in my next post) and met many amazing people. The data is coming in now and looking great. Despite minor setbacks along the way, the data collection is complete and I am excited to see the results and conclusions!  

2012-08-20T23:55:22-05:00 http://www.iris.edu/hq/internship/rss/interns/home_stretch

Now we're getting to the fun stuff! Actual visualized data. This map holds a place near and dear to my heart, if only because it showed that through all the coding and picking and re-picking and picking part 3, we've managed to get something. Even if it doesn't really seem to say much, results are results. Thus, you've just seen the focal mechanisms of twenty or so quality-controlled earthquakes that occurred in Oklahoma from 11/10 to 12/30. We had to toss out a lot of events along the way, unfortunately, because the picks didn't offer enough variation with either takeoff angle or azimuth. We then had to toss even more out because depths were too shallow to get a clear image, or there simply weren't enough events. The poor quality focal mechanisms were pretty apparent -- they were telling us that both thrust and normal faults occurred in this clearly strike-slip zone. Ah well -- survival of the fittest, earthquake style (except the earthquakes are at our mercy, a switcheroo from the typical where we're at the mercy of fault ruptures. Ha-hah!).  It looks like my last several days will be dedicated to visualizing the data in different ways in order to find trends -- for instance, color-coding events by depth or by time, creating a histogram of strikes, etc. This, unfortunately, is a little more hassle than I would wish, as GMT is picky and can't parse text files by itself, and thus every sub-section needs its own text file. I'm contemplating the pros and cons of automating the system -- pros, it would definitely be an aide to my mentors down the line, as they intend to continue with picking (I don't think anybody expected that we'd get 2/3rds of our events thrown out by either HASH or quality checks after HASH). Cons, I'd still need to figure out how to properly flesh out the code / make a more dynamic GMT script file / it might take more time than I have. I guess I could work on it after I leave Pasadena -- goodness knows I'll be flying all day Wednesday, I can test on my own computer, and SSH is really all I need to get something up and running on my mentor's server. I really can't believe that this internship is almost over. What happened to all the time? I just sold my bike on Craigslist, and have started wrapping up things here --  my refrigerator is conveniently nearing empty (after eating fajitas for lunch for four days straight), so I fancy that I'll do a blow-out, eat-at-every-place-I've-wanted-to-eat-at affair for the next several days. Hot dogs, pizza, cocktails, and Mexican food, here I come! I have been so utterly spoiled by the quality of the Mexican food here and in New Mexico; I don't know how I'm going to manage once I'm back in Rhode Island and all I have is a Chipotle. Life simply won't be the same.  Other things in life: more rock climbing, a lot more going to the gym, and a lovely weekend visit to San Francisco. I'm beginning to fall in love with California. There's still work to do. It's actually really nice that there's still work to do, because it's good to feel as if research / optimization is an ongoing process. Last few days, here we come! I imagine you'll hear from me shortly. :D Over and out!

2012-08-18T02:49:39-05:00 http://www.iris.edu/hq/internship/rss/interns/week_11_-_endless_checkerboards

August 13 to August 17 This week I’ve spent most of my time modifying my dispersion curve figures and fighting with this tomography code. It’s actually been going well and it’s been a very productive week, I finally managed to figure out how to set up the inputs properly. It was a complicated problem because the code only wants to consider arrival times for each separate period separately, and it needs to have all the same stations for each event in the same order. This would have been easy to accomplish if I had arrival times for every station from every event for every period but instead I had to find a way to make files that had the proper order of the stations and events and indicated properly the places in which I didn’t have data. Eventually I figured this out though and since I got that working I’ve been trying to run checkerboard tests. The idea behind the checkerboard test is that you make a model of a checkerboard of high and low velocity and calculate synthetic arrival times for your stations and events from that model. Then you feed those arrival times into the tomography code and see how good a checkerboard you get back out. When I started I was doing it incorrectly because I wasn’t actually creating the synthetic arrival times, I was just making a checkerboard pattern. Then I ran into several other errors but eventually worked around them and now it seems I am very close to being able to see the checkerboard pre and post inversion. I am not expecting to get very good inversions for most periods but hopefully some of them will have enough arrivals to get good coverage. The ones with better coverage we will be able to compare to Yoshizawa’s velocity structure maps. I’m excited about this step, but a little worried that to get any resolution from my checkerboard tests I will need to use very large squares which are low resolution and then comparing my maps to Yoshizawa’s will be uninformative. As of right now I seem to be running the checkerboard tests correctly but I’m not really getting any useful results yet, so I just have to keep trying different grid resolutions until I can get a good result. I’ll wait to post a picture of one until it actually looks like a real result. I wish I had more data, and it would probably be possible to get more data but it would take time that I just don’t have. Going into the last week here I’m still feeling optimistic about getting at least one good map to compare to Yoshizawa’s data and I feel that my dispersion curve figures are good and ready for analysis. To do that analysis I am going to attempt to process data from one of the earthquakes that Yoshizawa used to create his dispersion information. If I can get an arrival from one of his earthquakes to a station that I used and process that in the same way I processed my other data then I can compare the two dispersion curves and see if I’m measuring his values properly and what the effects of including the offshore values are. This weekend I plan on going to Questacon, the science center and back to the Old Bus Depot markets which I liked a lot, this time I’ll make sure to bring my camera! 

2012-08-17T19:05:10-05:00 http://www.iris.edu/hq/internship/rss/interns/final_day-_wrapping_it_all_up

So today is the final day of the final week of my internship and what a summer it’s been! I may still come in on Monday for some last minute things, since I don’t go back to school for another week, but I wanted a few last days at home just to relax since my grandparents are around. Plus, I’m still not done exploring California and this weekend I’m heading up to Lake Tahoe! As I expected when the summer got off to a slow start, this week has, inevitably, been pretty busy. I wasn’t able to finish the S-wave processing, but I was able to get it to a good stopping point so someone else on the team can pick it up once I’m gone. I did get through all of the preprocessing- stacking repeated shots, killing bad shots, creating fake geometry, creating log files, shifting first breaks, inputting real geometry etc…- and I’ll admit I’m not too disappointed that I don’t have time to do first break picks again! And of course, since I won't be back in this office again, I had to completely reorganize my life. After 11 weeks, both my computer and my desk were a total mess! I made sure to email myself anything I could possibly need over the semester, and tried to put together all of my files and notes for the next person picking up on this data set. I was also able to sit down with my advisor and another guy on the team and go through some old posters of theirs and talk through what I’ll want and need to do leading up to AGU. Never having done a poster before, I can’t explain what a relief it was for me to get a sense of what exactly is expected of me come December! Since I can’t remotely access the USGS server and continue processing data, my job this semester will be just writing everything up. My advisor is going to help me transfer figures off from ProMax, onto Illustrator, and then email them so I can make them poster ready. It means I’ll still have to figure out Adobe Illustrator once I’m back at school so I can manipulate the images, but it also means he’ll be able to go through everything I want to put on the poster beforehand. Now, just to look over some of my goals I had had at the beginning of the summer- I wanted to become confident and self-sufficient with ProMax and Unix. Of course I still had to ask others a few questions once and a while, and I was constantly googling Unix syntax, but for the most part I think I definitely achieved this goal. The S-wave preprocessing, which, at the beginning of the summer would have taken me forever since I had 489 shots to grapple with, went much quicker than I expected; it even went much faster than P-wave preprocessing. On top of that, for the past few weeks, I’ve had to teach most of what I’ve been learning to another student in the office who was away for some time. For me at least, having to teach someone something always solidifies my own understanding of it. I also wanted to become more comfortable with going out into the field. After we did my line in June, I haven’t had to organize any of our fieldwork, but I’ve had the chance to go out on five different occasions and by now, I feel more than confident showing newcomers or volunteers how and why we do things the way we do. Plus, I don’t feel completely lost in the warehouse anymore and I think I could explain reasonably well to anyone who asked what each tool we use is for and why we bring what we bring into the field. All in all, I think another success! My other goals and hopes, in general, all had to do with taking what I’ve learnt this summer and applying it to other situations, either by understanding more about seismic hazards and geophysics research, or by improving my programming ability, especially in regards to Illustrator or GMT. I haven’t touched Illustrator all summer and though I’ve used GMT, the script has always been prewritten in a C format, which I find easier to understand. Perhaps this semester I’ll have to work more on both of these programs, as well as others, when trying to put together my poster, but, as of now, they haven’t been touched. In terms of the ‘larger picture’ of our research, I do understand better how the work we’re doing can be used in more applied, practical situations. Two of the lines we did were for outsiders interested in water resources or liquefaction, which I wouldn’t have expected at the beginning of the summer. Plus, I was able to look a bit into what some of the other scientists in the Earthquake Hazards program were working on and it’s really helped my understanding of what exactly geophysicists do! My only regret is that I didn’t reach out more to some of the other departments and centers here in Menlo Park, given how wide spread my interests are. That’s definitely something that I will work on if I ever participate in similar research projects in future summers. So, all in all, it’s been an incredibly instructive and fun summer. Since I’m only a rising sophomore, I can hardly make any concrete decisions about what my plans are after graduation, but this has been a good opportunity for me to get a better feel for scientific research. Although I may not stay in seismology, it’s definitely convinced me to stay in geology and geophysics and it was one of the best possible experiences I could have hoped for following my freshman year!

2012-08-16T16:49:27-05:00 http://www.iris.edu/hq/internship/rss/interns/week_7_and_week_8

Week seven was my final week at Virginia Tech. I spent my time finalizing my tomography model and learning how to interpret it. My model shows several geological structures highlighted below in Figure 1 and Figure 2. Figure 1: The black stars on the model above show the location of three ranges. (left to right: Coyote Mountains, Superstition Mountain, and Chocolate Mountains) The seismic velocity through these ranges reaches a faster speed near the surface than in the valley between Superstition Mountain and the Chocolate Mountains. The circled area in the valley shows a shallow basement, which corresponds to the active geothermal Brawley Seismic Zone. Figure 2: The grey arrows point towards two faults on either side of the valley. The approximate location of the faults are located by black lines. The sharp change in the seismic velocity gradient indicate the location of the faults. With these interpretations, I wrote and submitted my abstract to AGU for the fall meeting. Throughout the next couple of months I will be fine tuning my final interpretations to create a poster presentation for the meeting. Week eight was spent in Idaho helping with IDOR. I arrived two days before the forty plus IDOR volunteers to prepare for their arrival and obtain equipment needed for the deployment of the 2,500 seismometers. By Wednesday morning all the volunteers and PASSCAL employees arrived for training. Volunteers came from several different states and four different countries to deploy seismometers. I joined them during training, where we learned the proper technique to deploy the seismometers and navigate using Garmin GPS devices. On Friday, we were sent out in pairs to deploy up to 50 seismometers across the seismic line at locations I helped survey in July. Saturday I joined a crew of three other volunteers on a four mile back-pack hike through Idaho National Forest to deploy twenty seismometers. On Sunday, the final seismometer was in the ground.   To celebrate a successful deployment we went on a geology field trip where we learned what other research was being done in the area. The day ended with observing one of the shots being set off and watching a meteor shower. Stay tuned next week to hear how the rest of field work went. Goodbye for now. Sincerely, Amanda  

2012-08-14T19:55:51-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_round_ten

Goals 10! Already! Weird, right? I go home in just 12 days. I need to add packing to the goals soon. • Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o I have the code working now, which is a major accomplishment because it means that all my inputs are functional. Most of the tomography code is written in FORTRAN so getting the inputs exactly right is important. o I am currently able to plot the outputs but I have realized that I will not be able to get a good inversion unless I include data from all the events together, instead of separately. That makes sense and I knew this would happen eventually but I’ve been avoiding it because it’s fairly complicated to make the inputs for more than one event. I had everything working for only one event. So getting it working for multiple events is the next step. • UNIX o Learn about Illustrator, start on poster soon! o Add comments! • Be able to produce a poster which describes my project that is up to professional standards for AGU • Explore Canberra o Go to the National Zoo and Aquarium or the Cockington Green Gardens o Go to Questacon – the science center I have also (once again) updated my figures to make analysis easier. I changed the way I plot the seismograms, before I was normalizing the raw data, plotting it, then bandpassing the normalized trace and plotting that, now I normalize the raw data and the bandpassed data separately which works much better for the scales on both. I also mentioned that I added the Rayleigh wave group velocity dispersion data from Yoshizawa last time. Now I’ve changed the region of the plot so it only shows the periods and velocities of interest, 20s to 150s and 2km/s to 5 km/s. Unfortunately, this means that many of the group velocity values I obtain aren’t plotted. It makes me sad to feel I am wasting them but they are probably relatively unreliable so it’s better not to plot or analyze them. I just added error bars to the Yoshizawa dispersion curves (The group velocity at each point is an average value and the error bar is the standard deviation). So now my figures are really awesome! I like them a lot. Hopefully we’ll actually get some good interpretation out of them, it looks like my values are almost consistently below Yoshizawa’s and the PREM predictions which is interesting and possibly indicates that offshore structures contribute to an artificially higher group velocity. A beautiful new figure: I’m actually re-processing these now to make the tick marks on top of the error bars a little smaller. We did some good exploring of Canberra on the weekend, we went to the Mint, the Parliament House and the War Memorial. I also volunteered at CSIRO which was fun, so I think the exploring Canberra goal is going well. At the Mint: At the Parliament House: I’m feeling pretty good going into my last 2 weeks here! It’s a short time but it feels like it will be long enough to accomplish something, we’ll find out soon! 

2012-08-14T03:24:03-05:00 http://www.iris.edu/hq/internship/rss/interns/finishing_up

Last week I was able to finally finish common conversion point stacking and get some really need figures. I was hoping to be able to only use the TA stations when creating these, but I found including the permanent stations from the New Madrid Seismic Zone as well as from USArray and IU stations has really helped the CCP stacking shown below.   Also last week I had the opportunity to visit a TA site installation. The amount of time and equipment that go into each TA station is amazing! It made me really appreciate of the stations I had to use ( about 50) and how much time went into getting them up and running.   As this is the final week of my internship, it is time to reflect on some of the goals that I had set back in the first week. My Goals were 1. learn how to use software to create graphs and visual representations of my research. - I have not needed to use GMT, which I thought I might need at the beginning of the summer. I have been able to create some figures with the matlab codes I was given. I think that I will continue to learn more about this as I begin to create my AGU poster. 2. produce a well written abstract to submit to AGU- with much editing help from my advisors, I was able to submit an abstract just in time. 3. read at least one paper every week that has to do with my research or any interesting research being done in seismology- I have read at least one paper a week and sometimes more! I think reading papers was the best way to find information on similar research that has been done. I was happy to discover that the more papers I read, the easier it got. 4. become comfortable with both water level and iterative deconvolution and be able to discuss it in an academic environment. - I believe that I have become relatively comfortable with many types of deconvolution, I hope to continue to learn how to talk about my research in an academic environment. A big test of if this has been accomplished will be at AGU. 5. try and visit all of the Smithsonian museums and become comfortable using the metro- Considering the number of museums in DC, I think I have done pretty well. I found that I kept going back to the natural history museum to look at the rocks and minerals and of course the seismology section but I was able to visit most of the museums. I have also become really comfortable with public transportation in DC and I take the metro everyday! Overall the internship has been an amazing opportunity and has made me really consider continuing seismology in grad school.

2012-08-13T14:47:30-05:00 http://www.iris.edu/hq/internship/rss/interns/week_ten-_one_more_to_go

So technically I’ve entered the realm of my final week here, but it’s been pretty hectic so I never had a chance to write a blog for last week! On Monday I had the pleasure of trying to get an abstract in for internal review here at the USGS. I had had two people review it over the weekend (since the deadline was noon on Monday), including my advisor, but then I was informed at 11:50am while checking through the abstract one last time with my advisor, that neither he nor my other reviewer could actually review it because they were also co-authors on the abstract (which had totally slipped my mind given that this was just internal review). So I began wildly searching the office for two new people to look at it (which was surprisingly difficult given that half the people were busy reviewing someone else’s abstract, and the other half were out at lunch). But finally I was able to get it to not two, but three reviewers who all had it back to me by mid afternoon. No one seemed particularly stressed out about the noon deadline, so that helped calm me down while I made corrections and then went through it one last time with my advisor. Finally, by the very end of the day I was able to give it in for internal review. They came back and approved it on Wednesday so I was able to submit it to AGU with a bit more time to spare than on Monday! I ran a few more migrations at the beginning of the week, but they were still not very satisfying so Rufus recommended that I just move onto S-waves rather than worry too much about it. As I mentioned last week, the velocity model has to be perfect and we just didn’t get data deep enough to make any solid conclusions about the model at depth. So in the abstract, I left it at stacking. Perhaps, once I’m back at school, we’ll be able to look at the migrations again and possibly get them worked out, but in the meantime I’m just not worrying about them. So, instead, I started looking at S-waves. With four days left here (my last day is on Thursday), I doubt I’ll get anywhere close to finishing them, but at least I can have them set up so someone here at the office can get right into picking, and not have to worry about pre-processing, once I’m gone. The analysis steps for S-waves are similar to P-waves, but slightly more complicated and immensely more tedious. Instead of 135 old FFIDs (original shots), I now have 489 (it’s still 118 channels, but we took at least 4 shots at each geophone). Like with P-waves, I had to create fake shot files and input a fake geometry (though this time actually based on all 118 channels, instead of 60 like with P-wave fake geometry) into Promax. I then had to create multiple log files to also input into Promax that used the field notes to label which shots were bad, which had to be stacked, and which were skipped. I also had to keep track of when the direction we were hitting the block changed in each set of points so I could then reverse the polarity of half the shots on Promax, so they all had the same polarity when I stacked them. Now I’m just in the process of checking through all 489 shots to find bad traces, as well as shots that look out of place in each set. Needless to say it’s going to take me a bit longer than it did for P-waves! Then I’ll have to really stack everything on Promax and shift all the shot points up, like I did with P-waves, and then I’ll be ready to pick, which given how noisy the data is, should be another challenge to look forward to this week. On Sunday though, we had a slight change of pace and went back out to do some fieldwork. I’ll admit, being at work at 7am on a Sunday wasn’t great, but it was nice to get out into the field again, even if this time we were going to a dump! The fieldwork took place at a landfill on the East Bay and took us all day. Apparently the landfill is slowly slipping into the bay (all that sits between it and the bay is a salt marsh that I believe is also a wildlife refuge). So a geotechnical company is going to put in a metal wall to act as a levee between the dump and the bay. But first they want a survey done to get a sense of what the subsurface looks like. We ran a 300m line along the edge of the landfill and then a 60m line, perpendicular to that, up a steep slope of mulch that undoubtedly overlain trash. However, being right next to the marsh and the bay, the view was really nice and the smell was completely bearable. Besides having to dig through two feet of mulch on the hill to actually reach dirt, it was a nice afternoon and we were able to get done pretty quickly. It was a nice way to spend my last weekend before I finish up work here!  

2012-08-13T11:50:26-05:00 http://www.iris.edu/hq/internship/rss/interns/agu_abstract_submitted

A followup on the statistical significance from earlier this week: A bunch of the groups didn't meet the criteria to test statistical significance of difference between waveforms occurring during night vs day. Those that did pass,  I would claim that as a whole, most of the waveform groups do not pass a test of 90% certainty of if the time intervals vary.  There are some that certainly show a difference, but most do not. We attempted looking at the waveforms of the groups that rejected the null hypothesis (that the night and day proportions were the same).  Some of our waveforms definitely had similarities, but those were from stations that often do hold such similarities.  Whether there were more during the night or day varied.   This week we also made a list of the last few scientific questions I need to tackle before I stop and work towards my ending presentation that ties it all together.  Here the ideas, and the answers to the ones I've answered. Does the centroid of the auto locations move during the month of auto detections? ans: no Is there any difference in the locations between night and day? Or do the IQ epicenters occur in the same places, and in roughly the same proportions?  No particulardifference in locations between night and day--epicenters generally appear in same cluster areas. Maybe just extended some b/c more during day........still working on proportions How do the strain rates vary temporally, and how do these compare with icequake event rates?  A comparison with GPS velocity timeseries (Automatically detected IQ rate) diurnal and multi-week timescales.  There are changes in strain rate patterns between Sept 24th and Oct 2nd, and comparison before and after that time period. Strange velocities seem to correspond with strange temps (?). Some velocity spikes post-oct 1st seem related to some event rates. At what distance are we no longer able to detect IQs? There's a period of strong "noise" (or is it signal?) that's recorded on all of the stations at some point in October. What the is it? Mike reports a move-out, and that it travels through the network. Basically, what's going on?  It travels up glacier. Is it recorded also on the bedrock stations? What's happening with the weather?  Don't notice trend with temp, wind--see weather_at_noise.png (note little pickup in rain) Maybe something with precip --For other examples from the Sept 26th, see rain_at_noise.png, Sept26_rain_waves.png Can we see it on bedrock: maybe at two, though they’re pretty noisy anyway, so hard to tell Can’t even necessarily see it on all the ice stations. It mostly shows up on line stations. I didn't notice anything suspicious with cross flow displacement or velocity. [except for that velocity is coming down from a strange high peak at the end of the strange time before then--as we saw in the figure with IQ event rate, temp and velocity.]   Basically where I've left myself right now is: I need to figure out at what distance we can no longer detect IQ. Maybe figure out why velocities are strange. Determine what cause of massive noise is, if possible. Figure out proportions of IQ occurence in area night vs day. This weekend I'm headed down to McCarthy to an area of Alaska I haven't been to yet!  Exciting!  And it's a wonderful celebration with Tim and friends!  Hooray! 2 weeks left, now.  I'll get up some fun pictures soon, I hope.

2012-08-10T23:58:20-05:00 http://www.iris.edu/hq/internship/rss/interns/pulsations_are_all_i_see

I have been very very busy lately. I have finally begun looking at EM data, which has been pretty exciting!! The way I narrowed down the data I wanted to look at was by picking 15 earthquakes using my beautiful earthquake graph (see in previous blog post) and then looking in my catalog (see in previous blog post) to see which ones had good data. Then I went through to find co-shaking signals in the EM data. We are assuming that if we do not see the actual earthquake waves arriving at our station, we most likely won’t see any precursors. We aren’t sure about this, but it was a way to narrow down the earthquakes. So I found 4 earthquakes that definitely showed those co-shaking signals and went from there. It took a lot longer to find co-shaking signals that I thought. At first I was just looking in the EM data around the time I calculated the earthquake to have arrived at each station, but I wasn’t sure what scales to be looking at the data at. I then figured out a way to plot seismic data with the EM data by converting and cutting my EM data so the times matched up. This was great because I saw the earthquake arriving clearly on the seismograms and then could look down to see what the EM data looked like at that time and if the signal changed at all. Below is an example of co-shaking signals. The top plot is one channel of seismic data and the bottom three are EM data from channels T1-T3 from our Parkfield station. You can clearly see the earthquake arrival displayed in the EM data. When I began to find plots like this, it was very exciting, and I knew I was close to being able to look at the actual EM data! As I discussed in my previous post, the first analysis we wanted to do was to look for the pulsations Bleier described in his paper as what he believes might be earthquake precursors. I had a neat opportunity to meet with Bleier and his team at Quakefinder to hear more about their company and to ask them questions I had about the pulsations and the analysis! The meeting was very interesting and pretty helpful. Since I had not begun looking at the data yet, I only had some basic questions to ask them, but it was helpful getting confirmation that what I thought they meant in their paper was actually mostly what they meant, for example about how they found the pulsations and where I could start. A big thank you to Tom Bleier and Clark Dunson for taking the time to help me out! I decided to look at our EM data in the week preceding the 10/31/2007 Alum Rock M 5.4 earthquake. This was the earthquake that Bleier found pulsations before and wrote about in his 2009 paper. I wanted to see what we could find on our data! I ran into some trouble getting the EM data using the ULFEM program that I installed onto the computer at Stanford earlier this summer. I ended up spending a lot of time trying to figure that out until we decided it was probably easier for me to download the data using the ULFEM program at USGS that doesn’t have the same problems. Darcy and Jonathan, my advisors at USGS, had me compose an email to the designer of the ULFEM program in hopes that he could help us with some of the bugs on the Stanford computer. It is a very helpful program and would be nice if future students working on this project could use it, as it would require much less programing, since it downloads and plots the data in multiple ways on its own. Once I got the EM raw data I wrote a script to help me filter and plot it. I needed to create a threshold above and below the mean in order to have a place to start to look for pulsations. After talking with Tom and Clark at Quakefinder, I decided to create the thresholds using 2 or 3X the standard deviation of the two-hour chunk of data I was looking at. I then went through, in increments of about 36 seconds looking for pulsations that exceeded my thresholds. This process is what I am working on now and has been going pretty slowly unfortunately, as there are a lot of pulses and it takes a while to save the pulse, record how long it is, whether it’s unipolar positive or negative or bipolar and find it’s amplitude. I have found some things to report on the pulsations though and was able to do some of that before my abstract was due, so I included that in there! You can see an example below of what two hours of my EM data look like, with thresholds indicated in dotted lines.  I have been recording pulsations that exceed 3X and 4X the standard deviation of the chunk of data I am examining. Essentially, the majority of the pulsations that exceed the thresholds are unipolar and the duration generally ranges from about 3 to 10 seconds long, usually averaging around 6-8 seconds. As of right now I am systematically going through and each day looking at two hours in the morning (9-11 UT), when the electric train BART is mostly dormant (making our data less noisy), and two hours in the afternoon (21-23 UT), when BART is on. I can say that these pulsations seem similar to Bleier’s pulsations in that they exceed a threshold of some kind and have similar durations. However, Bleier’s pulsations stand out much more from their data, which either means they are seeing much larger pulsations or our data is much noisier. And as I am looking through our data, I notice that the pulsations I’m picking out aren’t completely distinguishable from other spikes in the data; other spikes look similar in shape and duration, just that they don’t reach the same amplitude to put them over the thresholds. I am not convinced of anything yet either way for if these pulsations are related to the earthquake because I don’t feel like I’ve had the chance to look through as much data as I would like! What I would like to do with the data next would be to find a quiet week (in terms of earthquake activity) and pick a day to analyze the same way I’ve been doing for pulsations before Alum Rock. I want to compare a “quiet” day to see if the amount of pulsations has a significant change. In addition, so far I have been only looking on 1 channel of data from 1 station. I want to compare channels of data to see if I see pulsations occur on all 3 channels at once. If I only saw a pulsation on one it might indicate that the spike is merely something related to the machinery. I have definitely been working on a ton of different things this summer. I am feeling pretty overwhelmed with what I need to accomplish before the end of next week, but I am also very excited thinking about everything I have done! I am probably most excited about my work with MATLAB. When I actually think about the different things I have used MATLAB to do, I realize how much I have actually learned about it! I have a whole folder of MATLAB scripts that I have written mostly myself to do various tasks I needed to do this summer. While they are not the most efficient scripts, I have definitely learned a ton and hope that in the future I can learn more tricks and way to improve on my coding so what I write is more proficient.

2012-08-10T16:56:31-05:00 http://www.iris.edu/hq/internship/rss/interns/california_dreamin

Wow, this is it!  Today is my last day at my internship this summer!  Please forgive me for what’s sure to be a painfully nostalgic and introspective final post. I’ve been keeping track of my time left in the back of my mind but it still seems pretty darn surreal that my time at Stanford is over. The last few weeks have sped by, but looking back to the beginning of the summer—in Socorro, first meeting all the interns, hiking around in the brilliant New Mexico sun; or my anomalously rainy first day at Stanford, when I rushed in 20 minutes late after becoming abysmally lost; or how I spent a month without sleeping in the same place for more than a week—that seems like a world away now. I spent much of the first half of this week polishing up my abstract. My first draft that I sent to Simon was returned to me with as much red commented text as initial text. A few back-and-forths later, he pronounced my abstract “splendid,” and I submitted it to AGU with a day to spare! Since then, I’ve been working on my poster, exploring Adobe Illustrator (read: spending a comical 20 minutes trying to figure out how to insert images). I also tried to fit the stations I did to the West and Fouch "lithospheric drip" model.  It's not a very close fit; even with moving the center around, the average error is about 22 degrees.  However, even West and Fouch's results don't form a perfect circle, and as long as my data looks to be about in line with theirs, (which it does), I'm not too worried.  Relatedly, I did manage to improve the image I showed last week. I added a few more stations and fixed the resolution problem: (The different colors correspond to different data: the black stations are from our YX array; the red are from the U.S. Transportable Array campaign, and the lone blue station is data from a USGS station, cited in West's.) Ten weeks later, here’s my list of goals from the beginning of the summer. Let’s see how I did, shall we?   1. Improve knowledge of seismic methodry: how sensors work, how data is collected and interpreted.
 I’ve gotten some sense of this from the orientation and from my fieldwork in Elko. I have enough knowledge about seismic data to take down a station, and download the data… Being not very electronically-inclined, this is sufficient for me. 2. Gain facility with seismic data interpretation and the necessary software (related: improve computing skills, especially in UNIX and programs like GMT)
 My computer work mostly encompassed SplitLab, which I’m now a pro at. I’ve also used Matlab, UNIX, and GMT occasionally, and I feel more confident in each. I’m definitely not a coding whiz by any means, but I don’t feel like computers are impediments to my research! 3. Learn to connect seismic data to real features; in particular, to relate anisotropy to physical structures.
 It’s just the nature of my project that my results will never be as physically intuitive as, say, a seismic reflection profile, but I’ve become more familiar with the link between anisotropy direction and mantle flow. It was disappointing that I couldn’t distinguish between a crustal and a mantle signal, but when the data don’t support a hypothesis, I just have to find meaning in other aspects of my results. 4. Talk with professors and grad students, and become more comfortable interacting with people in an academic, professional environment.
 So. I’ve already identified this as my weak spot and, well, it’s not something that’ll magically resolve itself. This past week I’ve spoken (or, emailed and received no response from) Stanford professors whose work sounded interesting. Certainly I’m better at talking to grad students. I’ll keep working on this, and try not to get too upset with myself. 5. Construct a plan for after graduation next year. This part might involve researching grad schools and/or taking the GRE, even if it seems intimidating right now.
 Basically, this is all I've been thinking about lately.  I'm not going to lie and say that I've figured out my future over the summer, because I definitely haven't.  I've looked at a few school websites, and I'm still *pretty* certain that I'm going to apply to a PhD program.  If nothing else, this summer has reaffirmed that I do want to work in geophysics in some capacity, that I do enjoy research.  I think I just have to find the right project--it'll come, as long as I keep thinking and keep searching; it's just stressful and maybe a little terrifying to think about all the big changes that are looming on the horizon. 6. Enjoy spending the summer at Stanford! I've never spent more than a week or two at a time on the West Coast and I want to get the full California experience. Some things I want to try: surfing, In-N-Out Burger, and buying/cooking lots of local products. This. I feel like at least in this regard my summer was successful. I’ve been to the beach. I’ve been to the city (several times!). I’ve been to see a musical, to an art museum, to a picnic among the redwood trees, to the farmer’s market on California Avenue, and most recently, to canoe amongst otters, seals, and a multitude of jellyfish. I don't know how much more I could have gotten out of California, and I had a lot of fun living here! So that's where I am now.  Overall my summer was amazing, and I like to think that through the weeks of moving from place to place early on, through sitting in traffic on Highway 101 and finding that I wasn't angry, through the innumerable daytime hours and occasional evenings with my eyes glued to my laptop screen, that I've learned and grown in ways other than the strictly academic.  Certainly I've made some fantastic friends whom I'll miss very much and hope to keep in touch with them!  If nothing else, the people I've met and the places I've been this summer have made everything worthwhile.  I'm looking forward to going back home and being with my family, and, in less than a week, returning to Cornell and the family I've found there as well.  But I'll never forget the ever-cloudless skies, the fog creeping over the hills in the evening, the comfortable minimally-furnished room I've lived in, the midafternoon trips to the coffee machine with my fellow interns, the occasional glimpse of the Bay from a hill.  I'm excited already to return to the area for AGU, and to reunite with all the other IRIS interns!  So this isn't a goodbye; it's a see-you-soon.

2012-08-10T16:43:21-05:00 http://www.iris.edu/hq/internship/rss/interns/week_10_-_a_little_itchy

August 6 to August 10 I submitted my abstract and re-processed all my data and made new figures this week. It’s been very busy and productive! We decided not to include any results or conclusions in the abstract so we could focus on getting it in on time, which also gave me more time to try to figure out the tomography code. My latest figures include the dispersion from my data, the PREM predicted dispersion and the dispersion calculated by Yoshizawa. We have files from Yoshizawa that give Rayleigh wave group velocity at grid points. To get group velocity values to plot against mine I took the path between the event and the station, calculated all the points at 2 degree spacing along the path, took the integer value of those coordinates, extracted the velocity for that location from Yoshizawa’s data files and then averaged all the values along the path. This gave dispersion curves similar to PREM but demonstrate clear azimuthal variation that we can also see in our results. In general it looks like the results I get are more similar to Yoshizawa’s model than to PREM but also drastically different in some locations. One disadvantage to comparing to Yoshizawa’s data is that he does not have group velocity values for below 20 seconds period. It seems that the results I get below 10s are scattered enough that they may not hold any significance though, and I may change the plots to only show data between 20s and 120s. Here’s one figure that shows my results fitting more nicely with Yoshizawa’s than the PREM. And here is a different station from the same event showing a somewhat different trend. I’m looking forward to working on my poster once I (finally) get the tomography code working. I am making progress on that, it’s just slow going. So far I seem to have most of the inputs set up correctly, I’m just not sure what the outputs are or how to plot them. Once I get a better idea of what the outputs are I can more effectively change the inputs to suit my data. Effectively I don’t have much left to do, just get the tomography code working (I already have all the data necessary ready for this), plot my tomography results on the same plot and hopefully at the same resolution as Yoshizawa’s results (which I already have the data in the appropriate format for, I just need to plot) and then analyze the comparisons of my results to the PREM and Yoshizawa’s results. Then poster time! The question is, will I actually be able to get the tomography code running? So far I’ve only been working on it while waiting for other codes to run and now I’ll be able to devote my full energy to it. Hopefully I’ll figure it out soon. Last weekend I went with Archana, another intern, to the Old Bus Depot Markets and we ate some excellent pastries and had fun wandering around and looking at everything. I forgot my camera unfortunately so I don’t have any pictures from that trip. I’ll be sure to bring my camera for where we explore tomorrow, which is tentatively the Mint, the Parliament House, and Questacon – the science center. It will be a very packed day and I’m not sure we’ll make it to all three as they will be closing at 5pm. I’m also going to volunteer at a science demonstration for kids at CSIRO (the Commonwealth Scientific and Industrial Research Organisation) on Sunday so that will be fun! I’m enjoying my work and I’m feeling fairly positive about being able to finish the project and if not finish the poster at least get all my figures ready before I go. I still hope to comment my codes to make them understandable to other people and to myself when I’ve forgotten everything in three months but that will have to wait until after I’m done with everything else. I’m getting really excited about going home and also to go back to school! It’s been too long now, I’m grateful I took such a long internship because it has allowed me to actually get a lot of work done but I’m missing my family and friends. At the same time I’m also sad to leave my new friends here, but I’m really starting to itch to get back.  

2012-08-10T03:50:07-05:00 http://www.iris.edu/hq/internship/rss/interns/field_work_data_collection

We've made it out to the field for the deployment of the instruments. The original surveying crew met up with a crew of 50+ people from many different universities, who have banded together to lend a hand in the deployment. We've been mostly training so far, but are poised to head out into the field tomorrow to start. First of all we will be deploying roughly 2600 instruments along the length of the line. After that we will use explosive shots, each buried 90 feet underground so that no surface damage occurs, to send energy through the earth. This energy will be picked up by the seismometers and downloaded after the seismometers are retrieved. The roughly 24 teams will be split between two bases of operation, one in the west and one in the east. We will be deploying geophones connected to one-channel dataloggers. These dataloggers are RT125A or Texans and are primarily used for active source seismology since they have a relatively short battery life. The instruments are from the IRIS/PASSCAL instrument center in Socorro, NM. I am excited for the field work to begin and to perfect how to dig a hole with a pickax. The adventure begins tomorrow morning, bright and early for some and a little later for those of us heading west.  

2012-08-09T23:50:45-05:00 http://www.iris.edu/hq/internship/rss/interns/wrapping_it_all_up_and_goals_review

Well, amazingly, I'm in my last two days of the ten-week internship. It feels like it blew by so fast. First I'll go through a review of my initial goals... Since I didn't have to write the codes for this project I would like to understand what it is they are actually doing (I think I'm part way there on this). -I feel a lot more comfortable with most of the codes. Especially, the code for GISMO cross correlating. I never got a grasp of what the code for TomoDD, the earthquake location software, was actually doing, but I at least have a firm understanding of what goes into an earthquake location and how it is calculated. To understand the limits of the theory I am using. Does it over estimate or underestimate slip? Why? What does it actually tell us? -This one is a little more vague than some of the others unfortunately. From what my experience, it seems difficult to know whether it is under or overestimating slip in a region. There is a the possibility for counting too many earthquakes, but possibly an even more likely chance of not counting all of them if we missed a group of repeaters. What it is actually doing is giving us a pretty localized estimate on afterslip rate, more effective at depth than geodetic methods like GPS or InSAR. How does the theory relate to seismic hazard in the area in and around Christchurch, NZ? -This was a big one for me after my earthquake experience in Christchurch a little over a year ago. Although my project doesn't seem like it will support any direct hazard predictions, especially since my whole data set was before the Feb 21, 2011 quake, understanding afterslip rates on different fault segments is important for understanding stress build up and slip potential. If I'm really lucky, my work may give some sort of insight into why there was a second large event by the city after the 2010 rupture (the one I studied). I want to be good at producing good-looking figures by the end of this. :D GMT? -I think this was my most successful area. I can now comfortably explain and tweak a GMT code I created from scratch in order to make the map I want with GMT. Review of the manual is always necessary, but I now have the knowledge to do all of that on my own! Overall, this summer has been a wonderful experience both personally and academically. To be thrown into a new city with no friends at first seemed completely ludicrous, but after these ten weeks I would be completely okay with having to do it again. I had also never participated in research before this, and yet I am leaving with some GMT figures and a great data set to keep studying at Colorado College next semester. Who knows, maybe you'll see another blog post or two from me down the road. Thanks to Michael, Katie, my advisor Ellen, and of course everyone else involved in this IRIS experience and my time at Madison. This experience will undoubtedly be priceless moving forward in my seismological career.     Cheers! Ryan

2012-08-09T10:39:03-05:00 http://www.iris.edu/hq/internship/rss/interns/oh

It's been an exciting day today!  Firstly, I felt my first southern California earthquake! (USGS page!) It was a M4.4 earthquake, so it was strong enough to be felt and little else; I was lying on my bed when I felt the building jerk for a passing moment before falling still again. My first instinct was to hope that it was an earthquake for the following two reasons: 1) because it would be cool to feel an earthquake, and 2) because if it wasn't an earthquake, it would mean that my building had some rather major structural problems. Much to my relief, the USGS page was updated very shortly after the event, so my fears of a temporary eviction were dispelled. This is the second earthquake that I've felt -- the first was the Virginia earthquake last summer, an earthquake which inconvenienced some CVS employees when several items were jogged off the shelves. Secondly, and more related to my research itself, I have first-round results for my project! My mentor graciously did the third-time-around picking of the Oklahoma dataset last week (I was on vacation back home in Northern Virginia last week). The week before last, I had focused on writing scripts that would make focal mechanism calculation a walk in the park once we got the data. Of course, HASH and f77 were still picky and gave me a bit of grief, but I'm grateful to two-weeks-prior-me who threw together all the scripts. They ended up working quite well: there was script written to pull data from SAC, another script written to sort data from SAC into event folders, and my most darling script that took the HASH output, reorganized it, and put it into a GMT script in one fell swoop. Automation is beautiful.  Without further ado, the tinest thumbnail of my results (I didn't have the time to resize everything in GMT, so it looks like an incoherent mess of focal mechanisms right now): Look at those focal mechanisms. Look at all the strike-slip events! They're lining up along a fault that hasn't been mapped; the triangles are where our sensors were. I'm looking forward to going in tomorrow and making the data more readable / coherent.  It's weird to think that I only have two weeks left in Pasadena. This summer really has been lovely, but where has all the time gone? I find myself in a rush to use up all my groceries and Living Social deals -- I made a huge batch of black beans last night, but am not quite sure what to do with them now aside from eating them slowly on nachos. If anyone has any ideas on what to do with a lot of black beans, kindly pass the ideas on to me?  Well, that's all from me for now. No doubt I'll keep everyone posted on further developments. Cheers! PS: Even though she's already posted it, I feel like I should mention that I ran into Erin in DC this past Friday. I was just out in the city visiting some friends; funny how small the world is, huh?  

2012-08-08T03:01:57-05:00 http://www.iris.edu/hq/internship/rss/interns/time_to_reflect

Hi everyone, After finishing up time at Boise State University last week,  I have shifted gears in finishing my abstract (due tomorrow) as well as my poster.  I hope to finish as much as possible before heading off to Australia on the 25th of August! I've taken a little bit of time to reflect on my oustanding experience out in Boise.  I look back at the beginning of the internship at orientation in Socorro, thinking about how on earth I will complete a research project in a geology discipline that I have had no previous experience with at Union.  However, I realized that this opportunity with IRIS would be a great introduction to geophysics with complete immersion in a seismology-related project, and I just tried to absorb as much information as possible, both in orientation and at Boise State. I really could not have asked for a better project (though the other interns probably disagree!), with the incorporation of seismology concepts with induced seismicity from a geothermal power plant.  The combination of field work, analysis of a large set of data, and the incorporation of computer programs that were new to what I was used to, definitely sparked my interest in pursuing more geophysics work after my undergrad in geology finishes up. The AGU meeting this fall will only be a great conclusion to this experience, being able to present results from the past 9 weeks in an environment that will most likely be extremely overwhelming but rewarding!  I also look forward to see what the other interns were involved with this past summer, along with seeing what other research projects have occuring in the geophysical sciences.   With my term abroad trip to Australia and New Zealand this coming fall,  I'll be taking a tiny hiatus from the geophysics and immersing myself in marine biology and terrestrial ecology! I will probably do one more update on how everything is going, but I look forward to reuniting with all of the other IRIS interns in San Francisco this December!

2012-08-07T17:37:10-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_number_nine

This is the ninth edition of the goals (so many weeks!) I’ve noticed recently that the goals list is getting shorter every week instead of longer. I hope this is a good sign about what I’ve accomplished, not just a sign that I’m being more concise. • Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o Make a crude map of the velocity structure in Australia o Compare that map to Yoshizawa’s velocity structure map created using longer paths • UNIX o Learn about Illustrator, use it to create poster o Add comments! • Be able to produce a poster which describes my project that is up to professional standards for AGU o Register for AGU, sort out hotels and stuff as well • Maintain this blog about what I have accomplished and my goals • Explore Canberra o Go to the National Zoo and Aquarium o Go to the Cockington Green Gardens Unfortunately I don’t have any new figures for this post. I just finished re-processing my data because we found that cutting the traces to try to isolate the surface waves and then selecting more periods to try to get dispersion values for gave better results. I am much more efficient at processing it now! Hopefully this will be the last time I process it and then we will just look at the results for analysis and conclusions. Right now I do have comparisons to the PREM but not to the results from Yoshizawa, so finding and plotting those dispersion results on my figures is the next step for analysis. I now have all the results I need to set up the tomography, and once I can perform the tomography inversion on my data then I can compare it to Yoshizawa’s results in that form as well. So after I add the Yoshizawa dispersion results to my figures (if that is possible) then I will perform the checkerboard test to see the expected resolution for the tomography using my paths and then actually do the tomography. I’m excited about my progress! In other news, I went to the Old Bus Depot Markets last weekend which I really enjoyed! I ate a nice cinnamon pear danish and bought some vegetables. I’m hoping to go to either the Zoo and Aquarium or the Cockington Green gardens this weekend. Exploring Canberra is fun and there is no shortage of places to visit here. Till next time! 

2012-08-07T03:32:54-05:00 http://www.iris.edu/hq/internship/rss/interns/heavy_analysis

This past week has been really busy actually analyzing my data, so it has been difficult to gather all of my thoughts to update the blog.  Here are some of the hilights: Plots of all of the icequakes showed:         icequakes in clusters and linear formations that appeared to have no relation to prior crevasses         areas of icequake concentration spaced evenly (this has been checked by looking at the lowest magnitude icequake and seeing if we can tell it is there on all stations. The pattern is not a detection bias just because the icequakes happen to be near the seismic stations. A question here is why they appear evenly spaced. One idea is to look into tensile forces. Spread of magnitude are as follows: We checked the velocity we'd been using by looking at moveout and picking a best fit, which gives us the velocity. A box plot of the velocities gave us some of the following results: ~1.64 km/s as 50th percentile, ~1.69 km/s as 75th percentile, and what we used as our model was 1.67 km/s, so pretty good I'd say! I compared clustered waveforms (stacks of similar waveforms) over the night and day period. Making ratios to each cluster to the period (night or day) on a whole gives us a ratio, and we find that the relative percentages of the clusters to the whole are approximately the same for day and night (most of the time). Sometimes we see varying representations between night and day, but we still need to analyze for the significance (that's up on the plate as soon as the AGU abstract is up on its feet). I also worked on plotting waveform clusters on a map of the glacier to see if any waveform came from a particular area. Though there appeared to be some sort of patterns on occasion, I would say that there was nothing definitive. This turned out more challenging than anticipated, and I ran into coding problems.  [note: dark blue--> red represents largest--smallest of top 4 waveform clusters] With work from Mike and Tim, we've also been able to look at icequakes over a longer range of time, and they still appear in the same area. The diurnal icequake rate signal also remains until early October when the seismic stations got covered by snow.   I would say it was a difficult week because I really wanted to work on my AGU abstract so I could go through more drafts, but I simply needed more information from the data I was gathering.  It's really hard writing an abstract while you're finding out the results still!  But from my experience and what I've heard of others' experiences, this is generally how it goes...  Finally got a good draft though, I think! I'll include figures when I'm at the office tomorrow.  Also...down to the last 3 weeks.  Wow.

2012-08-06T14:22:11-05:00 http://www.iris.edu/hq/internship/rss/interns/week_nine

Last Friday I officially finished my ninth week at the USGS. I just can’t believe that the summer is coming to a close and I don’t know how ready I am to go back to school in only three weeks! Fortunately, my internship will continue for another two weeks, which is good given that I can’t remotely access the USGS server so everything needs to be done by the end of the summer. Rufus says we can work together on the poster remotely while I’m at school, but all data analysis and interpretation needs to be done by the end of summer. Last week, I generated a bunch of velocity models (examples below) and went through them all to pick the best one. I created one or two that used all of my picks in the inversions, without killing any, in order to compare what the model looks like with and without killed picks. For the most part there wasn’t too much difference, which is satisfying since it means none of my picks (even those that I killed) were terrible. In the end I chose three models that I think were best. When looking for the best model, I had to look for a version with the least number of killed picks, the model with the highest iteration number, and the model that goes deepest. The deepest I was able to get was only about 70m, but I was able to see a clear low velocity zone that corresponds to the fault strand we expected to find. Once I had my models, I had to extend them down to 5000m so we could stack and migrate them. In reality the extension is a fluke since you have to make up what you think the model looks like below what you can see. In the stacking it doesn’t make too big a difference, but in the migrations the velocity model needs to be close to perfect or else the migrations don’t come out properly. So for the stacking, I used a simple code that set the 2800m/s contour line at 175m, with data points at 5m spacing, and then extended that straight line down exponentially, with data points at 100m spacing, to 5km. Then using Promax, I created a stack for each of my best velocity models. I ended up with four stacks though, since I messed around a bit with the stacking parameters (stacking at a higher bandpass filter etc…). In the end most of the stacks came out really well. We could clearly see the west-dipping fault that we saw on the velocity models and it even looked like we were going to be able to see a few other fault strands, some of which showed a reverse component of motion, which is important given how reverse motion can effect earthquake shaking. All around, I was pretty pleased with the stacking results and felt confident writing my abstract. I would have liked to include information about migrations in the abstract to, but I wasn’t able to get the migrations to work last week. Because the program (which is a pre-stack Kirchhoff depth migration) is very sensitive to the velocity models, the process of virtually extending the model down arbitrarily meant that the migration results just weren’t as clear as the stacking results. I had to spend a while trying to figure out the code that extends the velocity model so I could manipulate it to carry down, for instance, the low velocity zone where we believe the fault to be, to more than 70m depth. This week I’m going to try my new velocity models to see if that helps the migrations at all. Last week I also finished up my abstract. Although they’re only due on Wednesday for AGU, we have to submit them to USGS on Monday for internal review. It’s apparently quite a process and unfortunately I was only clued into this fact on Friday afternoon, but I was able to quickly find two reviewers to look over it during the weekend and hopefully in the next hour and a half I can get all the paperwork together to submit it officially to the science center director! If all goes well in that department, I’ll be able to try some new migrations, and start working on putting together bits and pieces of my poster!  

2012-08-06T12:48:27-05:00 http://www.iris.edu/hq/internship/rss/interns/washington_dc_-_the_place_to_be

This past week began a little disappointing as I ran the CCP stacking code and which produced an image where it was hard to pick out the Moho and LAB. The first time I ran the code I only used TA stations which have not been in the area for a long time. Even with the "ideal parameters" I tried to find in the first part of the project, some of the TA stations on unconsolidated sediment had only 10-15 Ps and Sp paths that could be used in calculating the receiver function.  In order to try and improve the stacks, I am now working on adding some permanent New Madrid, US, and IU network stations that are nearby in the hopes of filling out the stack and hopefully making them easier to interpret. Other than that this week I worked on writing my abstract which I found difficult especially since I do not have great CCP stacks to interpret. I also found it difficult to summarize all the work I've been doing. At first I wanted to write every detail about everything I've learned, but after a few hundred words realized that I needed to summarize and pull out the most important points or no one would want to read the whole thing. To close out the work week I went to a delicious restaurant called Tonic about two blocks from my apartment for the summer and .... WOAH! I unexpectedly ran into Mya!!  We were both a little flustered and surprised to see each other but I was really happy to get to see a fellow IRIS intern way before AGU in December. Apparently DC is the place to be!  This coming week I hope to actually submit my abstract and really get some good CCP stacks that I feel would be worthy of posting to the blog. This coming week I hope to observe a TA station being put in with some people from IRIS HQ. It would be exciting to have a trip to the field, even if its just for a day!

2012-08-05T12:41:17-05:00 http://www.iris.edu/hq/internship/rss/interns/circular_anisotropy_or_i_actually_see_some_results

Only one more week left here at Stanford! It’s surreal how quickly time has gone. This past week my emotional investment in my research has increased dramatically, as I’ve graduated from the monotony of picking in SplitLab to the actual analysis of my results. I’ve been spending some time with GMT, my old frienemy, to plot the direction of anisotropy at the stations I’ve finished. I’ve tried two different methods of compiling the events per station—both a simple average and a stacking method that superimposes the energy maps produced in Splitlab. The second method seems more reliable, as it’s less susceptible to noise. Here is my most recent version of the graphic: Obviously, there’s still some work to do. The topography looks pretty pixelated, and I need to add a scale bar and axis labels. From the data I have, it doesn’t look like there’s any remarkable variation of fast-axis direction with backazimuth, which would indicate two-layer anisotropy. So, the hopes Simon and Mairi had had of being able to separate crustal and mantle signals probably won't come to fruition. What is interesting is how the direction seems to change spatially, rotating clockwise as you go west. This preliminarily supports a theory I’ve read about in a paper*, which proposed a “lithospheric drip” beneath the Great Basin of Nevada. One of the main lines of supporting evidence for this was a circular pattern of anisotropy formed as the lithosphere flowed inward. My map, the northeast segment of this circular region, certainly seems to agree with this geometry of anisotropy.   In any case, I'll have plenty to discuss in my AGU abstract.  Next week, expect lots of emotions and reflecting and thoughts. (as well as potentially a short review of Les Mis, which I'll be seeing in San Francisco next Wednesday!) * West, J. D., Fouch, M. J., Roth, J. R., Elkins-Tanton, L. T., Vertical mantle flow associated with a lithospheric drip beneath the Great Basin. Nature Geoscience. 2, 439-444 (2009).

2012-08-03T18:27:12-05:00 http://www.iris.edu/hq/internship/rss/interns/final_post2

Sorry I haven’t posted in a while! The past few weeks have become a mad dash to figure out what’s happening on the NAF. So to recap the last few weeks . . . I finished analyzing all the data for the 39 stations that were part of the NAF Passive Seismic Network. As I stated before, I’ve been looking for ambient tremor, as I turned up empty-handed in the search for triggered tremor. At first, the results of the filtered records for ambient tremor didn’t look that promising either. I’ve included a record from one of the stations (see below). I was looking for times when the amplitude in the tremor passband was elevated relative to the earthquake and surface waves passbands. December 2007 looked pretty promising for a few of the stations, and some of these stations were even placed decently close to the NAF itself or some of its major splays. As you can tell in the figure, early December looks a little better than later in the month. I chose a day when there weren’t any earthquakes identified and then filtered the records. I was looking for a signal that resembled what had been seen in other regions, like the SAF. Fortunately, there was a time that looks a heck of a lot like tremor, and the signal can be seen at several stations. However, the tremor had peak amplitudes from 10-15 Hz, and earthquakes had significant energy in the 2-5 Hz passband. Like I’ve said before, the methods used were based on other studies, and the above methods were appropriate for those other areas. However, with these unexpected differences in tremor and earthquake energy, these methods need to be revised a little to make them more suitable to study tremor on the NAF. So what does this mean for tremor on the NAF? I’ve probably identified tremor, but first changes need to be made to the methods before we can start characterizing it for this fault zone in particular. I’ve been talking to Dr. Warren, my advisor, about the possibility of continuing this research for my senior Capstone project that I’ll need to complete this year. This project could go in many different directions right now, so I’m not sure if I’ll be the one to try adapting the methods or if I’m going to look at something else. I need to talk to my advisor at school first. Regardless of what happens during the school year, I’m pretty happy with where I am ending things this summer. Today’s my last day in St. Louis, and I just submitted my abstract! I’ve also begun working on my poster for AGU. I don’t have anything too concrete right now, I’m just deciding which figures most effectively demonstrate the results of my project and also am in the (very) preliminary stages of writing. This summer has been a wonderful and incredibly rewarding experience. It’s amazing to think about how far I’ve come since my first day. I’m looking forward to meeting up with the other interns again in December to see what all their hard work looks like in poster form. Well, I should get back to work seeing as I only have a few more hours left. It’s crazy how fast the time has gone! That’s all I have for now. The rest will be at AGU.

2012-08-03T14:10:04-05:00 http://www.iris.edu/hq/internship/rss/interns/week_9_-_the_trouble_with_time

July 30 to August 3 It’s getting closer to the end here and very close to the abstract submission deadline! I’m currently on my second draft of the abstract, and I’m going to process my data and try to get that tomography code working before the final draft and submission. I just joined AGU yesterday so I’ll have to wait a couple more days before registering for the meeting. I’m quite excited to go! Hopefully in my last week here I’ll spend some time learning Illustrator so I can make, or at least start on, my poster. If I can’t finish the poster here I’ll need to think about how to transfer the necessary figures to my laptop before going. I’m going to miss everyone here and I’ve made some good friends but I’m also very excited to be heading home and then back to school. I plan to submit my abstract to the Seismology General Contributions session and request a poster so I’ll need to make sure everything for my AGU registration is working on Monday. For now I’m trying to see if there is a way I can cut or filter the data differently in order to extract more results. Today was a very unproductive day, which is always disappointing but I have high hopes for next week. There were many interruptions today because they were rearranging the room where I work, there was a going away party at tea in the morning for the director of RSES, I had a meeting, and there was an hour of lecture and an hour of tutorial for my adviser’s Physics of the Earth class. Also, my Ethernet cable went missing somewhere in the process of them moving everybody’s desks around so I need to get that back. Thrilling stuff, I know. Even though today was fairly underproductive, I think this week was actually fairly successful overall and I now know which data I can use and how to use it and all the processing and plotting codes are working. I’m just going to try to improve the results next week and get the tomography code working. If I can do that by Tuesday then I think I’ll be in really good shape for submitting the abstract - its fine now but I’d really like to be able to add some real results instead of just aims and hopes. On the home front I made banana bread twice. And forgot to take a picture both times, sorry! Here’s a cool one of one of the animatronics at the dinosaur museum instead, though! No particular plans for this weekend yet but hopefully next week’s blog will have some exciting pictures of wherever we go! And also some good (and maybe finalized) figures! I’m looking forward to my last three weeks here; I know it’s going to go by quickly. Perhaps too quickly for all the work I want to get done, but in some ways not quickly enough because I’m really feeling ready to go home. I think that’s always the trouble with time though. It always goes too fast and not fast enough, all at once. I’m sure Cheers! 

2012-08-03T05:39:15-05:00 http://www.iris.edu/hq/internship/rss/interns/back_with_some_eq_locatons

Now I finally have my earthquake locations to constrain repeaters more thoroughly than just by the shape of the waveform. Some of the families turned out with very similar locations such as the one below (segment C) and some did not. Overall, at first glance it looks like I should be able to make interpretations about which fault segments are more prone to repeating clusters and which aren't. In the map below, red earthquakes are at depths less than 5 km and yellow are between 5 and 10 km. Eventually, I will make some maps to show the temporal spacing of earthquakes within families as well. Now that I have some idea of what my data looks like I'll be able to get a few drafts of my AGU abstract in!   Goals for the rest of the internship: Search for more repeaters on some of the fault segments that didn't appear to work so far. Run a program called HypoDD, which should allow me to get some sort of error bars on my map. (hopefully they aren't massive!) Get my abstract well-polished and turned in. Potentially, stack some of the families of waveforms to see how the families differ overall.   Cheers! Ryan

2012-08-02T14:22:36-05:00 http://www.iris.edu/hq/internship/rss/interns/go_to_blog_post_2

Whoops, I've been overdue on a blog post!  This post will be dedicated to the week of 7/16 to 7/20, where I spent all of my time modifying my picks on Antelope (hence the title). The data had just been refiltered, so I spent my days readjusting my P and S picks. The TA stations had considerably cleared up with the filtering, but for some reason, other stations fared less well; we discovered later during the week that the newly applied filter had failed to correctly account for sampling-loss rate from the original acausal filter. It went something like this: Station takes 200 samples per second Acausal filter reduces it to 100 samples per second A filter was applied to convert acausal data to causal data, but filtered at 200 samples per second Data gets fuzzy So thus, it turns out we needed to refilter the data again. Excitement! In other general news, I joined a rock climbing gym and took a free archery lesson. Southern California truly is lovely, absolutely abounding with things to do!

2012-07-31T14:30:54-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_version_eight

While I haven’t done an actual analysis yet, it is now possible! I’m very excited about my new figures. Here is the eighth update of the goal list, crazy how time flies! • Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o Use the good data for tomography to make a crude map of the velocity structure in Australia  Learn the tomography code!  I’ve started work on this and I think I’m making good progress so far, I’m working with examples and following through the instructions. • UNIX o Learn about Illustrator o Add comments! • Understand what group velocity dispersion is used for and be able to communicate knowledgably about it o Read papers and thesis from someone at ANU concerning group velocity dispersion. • Be able to produce a poster which describes my project that is up to professional standards for AGU o Select the good data from the new figures o Register for AGU o Submit abstract to AGU • Maintain this blog about what I have accomplished and my goals • Explore Canberra o Go to the National Zoo and Aquarium o Go to the Old Bus Depot Markets Here is one of my new figures, I’m pleased with them! Now I just need to run the code for all my data and look at all the outputs. I’m just waiting on my adviser to see if the layout is ok and if there’s anything else we want to add to the plots before printing them. After they’re all printed we’ll sit down with them and go through and only keep the ones with visibly good data. Then it will be time to use the tomography code to invert the travel times and make my first map! I’m really hoping to do this before August 8th, when we will submit the abstract for AGU. We went to the National Dinosaur Museum on Saturday! It was really fun; there were fossils, sculptures, replica skeletons and animatronics. His teeth were actually pretty sharp! 

2012-07-31T02:27:06-05:00 http://www.iris.edu/hq/internship/rss/interns/lets_do_some_interpretations

So finally I have my data set almost completely analyzed! Today I started the last step which is sorting my earthquake families and pick arrivals into the proper format and organization to run through the relocating program. The set up takes about an hour and the program should take a couple hours to run when I start it up tomorrow!  Next time I'm back on the blog, hopefully Thursday, I should have a fairly complete dataset to interpret and make some maps with! I will be having a meeting with my advisor on Wednesday to discuss what the scope of my interpretations will be based on how my data set comes out (fingers crossed). Sorry I don't have any cool figures to post now but some will be coming soon; I promise! Wednesday night a couple friends from Colorado will be coming in to visit for a night. Glad to be merging the Colorado and Wisconsin groups finally! Be sure to enjoy the Olympics everyone, and for your entertainment from a Colorado College (:D) professor... http://www.coloradocollege.edu/newsevents/newsroom/dan-johnson-the-man-who-predicts-medals Cheers! Ryan

2012-07-30T21:53:54-05:00 http://www.iris.edu/hq/internship/rss/interns/imaging_mudpiles_-mississippi_embayment

Last week was spent finishing up more single receiver function parameter changes and started writing about each specific case. It was helpful to have some time to actually sit back and think about what all of the work and calculations I've done really mean. It was also helpful to think about the specific geology of each of the areas. In addition to the Mississippi Embayment/Realfoot rift area, I had been hoping to have time to look at CCP stacks of the area under the Mid-Continent rift. To at least start this I have created a list of TA and permanent stations that I will use this week to request data and hopefully have time to get to before the AGU abstracts are due. I was able to also start preparing data for CCP stacking which I have been really excited to get to. A new code was just given to me today that would make the CCP stacks better than using the iterative time domain calculations that I had been preparing to use. The new method is  called the  Extended-Time Multi taper Receiver Function Estimation Technique and was created by George Helffrich (2006) and improved by Takuo Shibutani, Tomotake Ueno, and Kazuro Hirahara (2008). This week I hope to look into what this code actually is doing by reading these papers and talking to my host about the code. While I figure out what this code is doing I hope I will be able to prepare all of the data and get CCP stacks that are interpretable. I am a little nervous that the sediment layer on the Mississippi embayment  be a huge problem in interpreting the data despite the large number of stations. All I can do for now is hope that it will all work out well. This week is also the last full week before AGU abstracts are due! This means that in addition to finishing everything I can I also will have to start writing about what I can present at AGU. This will be the first abstract I am writing so I am a little nervous but also excited! Until next week!

2012-07-30T17:30:46-05:00 http://www.iris.edu/hq/internship/rss/interns/the_final_week-_wrapping_it_up

Hey All, So this is my final week out in Boise, and I have to say, it seems like just last week that I got into Boise!  ~9 weeks later, it's about time to begin wrapping up my research out here.  I've begun writing my AGu abstract, which I'm not too stressed about.  Even though it's somewhat difficult to summarize 2 months of research into <200 words, I think I can handle it and will definitely get it in by the 8th of August.   This past week has been pretty busy for me.  During this time I've gone through all of the passive seismic data recorded at Neal Hot Springs since last May, over 400 days of data.  As I was working through the ample amounts of data, it seemed like on most days during a specific time interval, there was definitely characteristic fluid flow seismic waveforms that were being generated on the 10 seismic stations I am analyzing.  Identifying the fluid flow events was the somewhat easy part (aside from deciding what is actually fluid flow and what is truck/man made noise).  The difficult portion of looking through this data set, which took close to 5 days to analyze in depth,  was trying to see if I can identify local events.  It was like searching for a needle in a haystack, except there was no needle (so we think).  Many of the events in the system were already catalogued through the NEIC database, but I was trying to find local events with frequencies greater than about 10 Hz, that were not catalogued in the event.  Once I find these events, I can go in and look at P-wave arrival times relative to each seismic station so I can estimate the direction the waves are coming from.  Unfortunately, only two very local events were found in the database, and these events appear to be arrving aprooximately 20-50 km outside of the Neal Hot Springs area, which suggests that these events were not caused by the fluid flow.  In a way this conclusion is great news for US Geothermal, in that their geothermal power plant is not creating any significant seismicity that could ultimately affect production.  At first I looked at my finding and thought, "Wow all that time wasted, searching for something that does not exist!"  However, after review and looking at the larger picture of this project, going forward if further monitoring of these stations shows that there is in fact an increased in seismicity located very close to the production zone of the hot springs, then it can be assumed that a recent event that the geothermal company began performing must have caused the seismicity.  Below you will see a map and a P-wave arrival screenshot.  These waveforms come from a non-catalogued event that most likely originated to the northeast of Passive Seismic Station 4, not in the area of geothermal production.  I'll do another blog post later this week to truly wrap things up!

2012-07-30T16:39:35-05:00 http://www.iris.edu/hq/internship/rss/interns/week_61

After finishing up surveying for IDOR on Sunday, Monday was spent cleaning the vehicles and doing last minute tire repairs. Then it was back to Virginia on Tuesday. The first day back at Virginia Tech, Wednesday, was full of data processing for SSIP. I spent the day sorting the first arrival time picks. The purpose of this sorting was to take the 100m spaced receivers in the valley and to choose every third receiver in order to have spacing in the valley that is similar to the spacing of receivers outside the valley. Then on Thursday I used the newly sorted picks to create another tomography model. This model along with the previous model were fine tuned on Friday. The resulting models ,shown below, will be used to interpret the subsurface geology of the Salton Trough. The models are grouped based on the parameters used and whether the picks were sorted or not sorted. The groups are organized even further by smallest to largest iteration number. Iteration number is the number of times the tomography script produced a new model every third time using different smoothing. The tomography models above are of non-sorted picks. The tomography models above are of sorted picks. Stay tuned next week for my analysis of these models. Goodbye for now. Sincerely, Amanda  

2012-07-30T16:09:01-05:00 http://www.iris.edu/hq/internship/rss/interns/week_eight

Another week has gone just flying by, though I think I’m really starting to make progress, especially since first break picks are finally completely done. After I had done my picks last week (and redone them, two or three times!), I exported them from the ProMax database into an Ascii file on the terminal. I could then use a KILL file I had created listing all the traces I hadn’t been able to pick/ places I was unsure of my picks, to actually remove any of the bad picks from the Ascii file. Then using a premade code, I went through this file and did four different checks, including reciprocity, to quality control my picks. And of course, after I completed each test, I would have to go back and fix the database, reexport the data and run the test again. Needless to say, I was crossing my fingers for it not to give me any errors each time I ran the tests! The first test listed any picks that were less than or equal to one and picks that were above a maximum value I input. The second test listed any picks that differed from their neighboring picks by more than a certain max amount. The third test listed picks that decreased (the time became shorter) with increasing distance from the shot. Even if one pick was just a millisecond above the one before, it could really throw off the data given that it would be physically impossible! The final test was the reciprocity test that I mentioned last week. This would go through and compare the travel time for a shot between the shot point and another geophone and the time for a shot to travel from that other geophone to the initial shot point. It was inevitable that I had a few that were off, but as long as they were under 10 milliseconds or so, it wasn’t a problem. It didn’t take too long to fix most spots, but of course once you change one set of picks, you have to go through to make sure it corresponds with all the following picks. The next step was to invert the first picks for the refraction data and turn it into a suitable velocity model. Making the inversions isn’t too difficult, but it takes the program (written by fellow IRIS interns Amanda and Rachel’s mentor) a while to run. One has to also create multiple versions as well, each with slightly different inversion parameters- initial velocity model, grid size, smoothing parameters etc…. Unfortunately, the GPS readings from the line are all off because of tree cover, so I haven’t been able to input the real geometry yet for the line. But, because the inversions need elevation data, I had to trace out my line the best I could on Google Earth, record the elevation at points 5m apart, convert elevation from feet into inches, and then turn the raw elevation data for each point into distance above the lowest point. It’s not a perfect method, but it does let one add a sense of the topography into the inversions. Once the inversion program finished running, I can run a GMT program that turns the inversions into an actual image of the velocity model. Each version produces 30 or so iterations and so I’ve had to go through and choose the best iteration for each version and compare them to get the ideal velocity model. However, I realized last Friday that I had reversed the elevation data so it ran East-West, while my shot point data runs West-East. That meant I had to go through and recalculate the elevations on Google Earth and rerun the inversions. I would have then gone through all of my velocity models on Friday, but I had to leave that until today since I left work early on Friday to drive up to Yosemite for the weekend with my family. I’ve been in California 3 years and have never made it up, but needless to say it was an AMAZING weekend! Of course it made getting up early again this morning for a Monday at work quite difficult!  

2012-07-30T14:00:39-05:00 http://www.iris.edu/hq/internship/rss/interns/week_six-_back_to_virginia

After landing back in Virginia I post-processed the GPS data and worked on my abstract this week. In the field our teams of two were split into separate jobs, one person hammered in the stake while the other person used a highly accurate GPS device called a Trimble to record the latitude, longitude and elevation of the stake's location. These data were stored in the device until the data from all four devices were downloaded into a university laptop. Though highly accurate, the accuracy of the points can be further improved through post-processing. I spent the first part of the week after arriving back post-processing the data. In essence, the data is fed through a program that searches out permanent GPS locations nearby to the data point recorded by the Trimble. It then uses these locations to refine the recorded locations to make the measurements more accurate, which is important in the code that will be run later. We are headed back to Idaho for deployment on Sunday, to meet up with our large crew. I am excited to be part of this project 

2012-07-29T22:04:17-05:00 http://www.iris.edu/hq/internship/rss/interns/week_8_-_kangaroos_and_dinosaurs

July 23 to July 27 Well hello again all, the time seems to just slip by! That AGU abstract deadline is just around the corner; I hope I actually have some results by then. Work is going well here and I feel very productive most days. I recently discovered that for some of my data there was another, smaller event recorded near the end of the time that I was investigating for some of the stations, but it shouldn’t take too long to go back at cut the traces a little shorter. By the end of Monday I hope to have produced the new figures of the data so we can go through and pick what is good enough to keep and what has to go. Then after we’ve selected the good data we can invert for velocity structure and create the first rough tomography map! I’m very excited about this and the progress I’ve been making, I feel that the project is chugging along. I’ll share some images of the data on Tuesday, and that’s about it for this week! In unrelated news I’ve been practicing making my own bread. It’s a good wayt to spend some time and I enjoy it. This is my third loaf: This one has a much nicer shape than the first two because I actually bought a loaf pan. I plan on making some banana bread soon as well, if it turns out well I might even post a picture! I’m very spoiled at home and in my dorm in California where I have lots of cooking tools and pans and ingredients stocked up, but I’m very pleased with my new loaf pan and there’s a muffin tin at the house here so I’m slowly expanding my baking enterprises. This weekend I will go and see the National Dinosaur Museum with Marija and Archana, we will miss Debjani though because she left early this morning. Hopefully there will be some cool pictures of the dinosaurs for next week’s post; apparently there are skeletons, sculptures and animatronics! I’m very excited. Last weekend we went on a good adventure to see some kangaroos, and took some great photos. Here is one that Debjani took. Cheers! 

2012-07-27T21:48:54-05:00 http://www.iris.edu/hq/internship/rss/interns/picking_along

Once again, another week has flown by in a blur of SplitLab picking. I’ve been skipping stations in order to finish the B and C lines, but they’re spaced closely enough that I should have still have good coverage (and if I get bored during the fall, I have something to do). Last weekend my parents and my brother came to visit me, which was fun. It’s been horrendously hot in Wisconsin, so they enjoyed getting out to dry, moderate California. We passed the time in the traditional Golos Family Vacation Style, which is to say, spending every waking moment driving, eating, hiking, walking, or otherwise frantically trying to take in all the sights of the Bay Area. In three days, we managed to cover Berkeley, downtown San Francisco, Año Nuevo State Park (again for me, though we got to see elephant seals this time!), Butano State Park, Santa Cruz, Sonoma, as well as the Stanford campus. It was exhausting, but really fun to more parts of the region, and to hang out with my family, since I’ve only spent a week at home since January! Because most of my week at work was spent picking, I don’t have many images that will look too different than what I’ve posted here already. Simon warned me earlier this week about “getting lost” in my event-picking and losing sight of the bigger picture of the project; I could definitely see that beginning to happen, so I’ve on and off been tinkering with a GMT script from a grad student that will plot the splitting parameters for each station on a map. It’s hard to change my focus, though, when I’ve been in the Picking Zone all day and I just want to get through as many stations as possible. My general approach to working has always been to just grit my teeth and slog through, even if—especially if—it’s a tedious task. So I guess this is another example of how doing research can be really challenging in subtler ways than the usual coding problem: I have to learn to be flexible in terms of how I prioritize my tasks, and learn to be able to switch mindsets quickly. Fortunately, I should be wrapping up my picking today, and next week will begin the fun stuff—trying to actually connect my SplitLab results to the anisotropy structure beneath the Ruby Mountains. I’m excited and a little apprehensive for this part. I chose this project because I wanted to see how to make this connection between seismic data and actual geology. So in a way, these last few weeks are a test, to see if this is really the sort of work I want to do in grad school. And more immediately, it’s also a test of my SplitLab skills—I’ve spent nearly two months learning and using the program, so hopefully my data will yield some sort of meaningful result!

2012-07-27T18:25:51-05:00 http://www.iris.edu/hq/internship/rss/interns/one_million_clicks

My internship is starting to wrap up. We’re focusing more on analyzing our results and discussing the conclusions of the project and less time picking earthquakes. I’ve been working in GMT and matlab to produce figures and attempt to find some quantitative results. Meanwhile, some of the people I’m working with are drafting a scientific paper. The work I’ve been involved in this summer is a very preliminary study. The goal of the project was mostly just to see if there is any seismicity at any of the volcanoes where seismometers were deployed and if any of them might warrant further study. I’m struggling a little with the uncertainty that I guess is inherent when doing science in the real world. It’s sort of tough to balance honestly representing your findings and drawing significant and interesting conclusions from those findings. I feel like we’ve mostly accomplished the goal of determining which volcanoes are more seismically active, but we can’t say much about what might actually be happening or precisely where. I calculated that I have clicked more than a million times in the antelope database to pick all of these earthquakes. It’s been a great summer. If I choose to go to graduate school for seismology I will have a lot better idea about what I’ll be in for.  

2012-07-27T11:17:36-05:00 http://www.iris.edu/hq/internship/rss/interns/week_8

Since I last posted, I finished all of my picks for my second time frame, and I just finished all of the locations, which means I'm back to what I'll be doing with them and how I want to make comparisons.  I've started reading up a bit again, and getting some more ideas of what types of patterns to look for in my data.  I have at least one more article left on my 'to read' list... and I'm sure I'll find more. I know I didn't have any figures last week, so I'll include the complete histogram of events I've picked once I figure out how to make it!  (Mostly I still have some trouble figuring how to call information out of the database correctly...) Also, my parents came up over the weekend to visit, and travel around the rest of Alaska.  I went with them on the bus tours at Denali, and flightseeing up to Mount McKinley.  It was amazing!  I got to see an amazing display of crevasses, which is a significant portion of my project, so it was great to see it in person.  When I get the histogram and my photos made/downloaded, then I'll post them up here! Here's the histogram!

2012-07-26T19:18:54-05:00 http://www.iris.edu/hq/internship/rss/interns/week_51

This week was our second week in Idaho and Oregon surveying sights for IDOR. The majority of our week was spent in the beautiful Idaho National Forests, which was home to a diverse group of wildlife and several geological structures. The photo above shows part of the survey crew in Challis National Forest. Throughout the week, the group got to visit a seven foot high fault scarp, natural hot springs, Craters of the Moon National Park, and an old copper mine. The following pictures show some of the things we got to see. The photo above shows a natural hot spring pooling up on the left banks of a river. The photo above shows a few splatter cones in Craters of the Moon National Park. The photo above shows a rock collected at an old copper mine near Mackey, Idaho. The photo above shows an old mining building at the same copper mine. Although the trees and mountains were not conducive to the GPS locating satellites, it was fun  to work in that environment.  In the forest the  group saw several varieties of gophers, a black bear cub, mountain goats, elk, deer and antelope while working. We successfully finished surveying the almost 3,000 sights on Sunday, July 22. Our final total of flat tires came out to be ten.  The final total of different hotels we stayed in came out to be seven. The final total of laughs and smiles came out to be too large to count. I look forward to returning in August to deploy the seismometers to our surveyed sights. Stay tuned next week to hear about my time back at Virginia Tech working on SSIP data. Goodbye for now. Sincerely, Amanda  

2012-07-26T12:47:03-05:00 http://www.iris.edu/hq/internship/rss/interns/on_the_6th_day_of_ramadan_my_mother_packed_for_me

Hey everyone!   These past couple of weeks have been pretty exciting in the antelope world. I've analyzing the month of data in which a 7.4  magnitude earthquake occurred in the region where the seismometers are. Seeing the seismographs from when the earthquake hit and their aftershocks are very interesting and quite captivating.  At first, it was a little frustrating to Reorganize the associated picks, but through much practice it got  easier. I am now looking at the previous month to hope I can move onto a couple of more months to analyze and get more data to support a strong abstract (a very big goal I'm working to achieve). I also have to revisit gmt and scripting, so I'm in for a busy, but always progressive final weeks of the internship. outside of the lab, my summer keeps on going smoothly! Hanging out with friends, going home every now and then, and it Ramadan! Ramadan is a great way to get much of my lab work done. The more I work, the less I think of eating and/or drinking. It's safe to say progress is increasing in the lab. Calvin left a few days ago so now the people who remain in the lab room are my two roommates and a grad student.  Well that's it for now, I'm pretty stoked to see how the final weeks turn out.   Noor

2012-07-26T07:55:41-05:00 http://www.iris.edu/hq/internship/rss/interns/week_five2

we've just finished up the surveying field work and now I am back in Virginia for a little while before the deploying begins. I worked in the field with a great crew. We had a lot of great experiences and rock hounded all across Idaho. I return to Virginia with a collection of obsidian, garnet, flourite, petrified wood and many other varieties.  We placed nearly 3000 stakes, with the line stretching from far eastern Oregon as far east as just past Challis, ID.  We stayed in small towns all over Idaho and met all manner of people.  The field work consisted of following garmin waypoints to the line and working on each segment in teams of two. At each waypoint station we hammered a stake with the corresponding number written unpon it and took a Trimble reading. The Trimbles were highly accurate GPS devices that took highly accurate readings (with accuracies down to 20 cm in some places) that are nessecary for the data processing. 

2012-07-25T11:52:54-05:00 http://www.iris.edu/hq/internship/rss/interns/a_change_of_gears_in_the_home_stretch

Hey everyone, During past week and these past couple of days, my advisors and I have decided to take a direct our attention away from receiver functions and begin to look at induced seismicity at Neal Hot Springs over the last year.  One of my advisors is still working on the receiver functions, and I think he has discovered the problem that we were having, which lied in correctly calculating the back azimuth.  Since we just figured this problem out and I have less than two weeks left out at Boise State University until I return home, I figured in order to produce semi-quantitative data for my poster, it would be best to go back and explore induced seismicity.  So far this change of gears has been successful, and by the end of these two weeks I hope to come out with some nice figures and results. This part of my project will included quantitatively looking at fluid flow events and local earthuakes caused by the geothermal fluid flow in the seismic records going back until last June.  One method of locating and logging these events has been to use a spectrogram in the frequency domain to help identify/ classify the type of seismic event that is occurring.  For example, a fluid flow event will have a much different spectrogram image than a teleseismic event, which will have a different spectrogram image than a local event.  Typically, the teleseismic events will be characterized by their lower freuencies (<1 Hz) while the local events will have higher frequencies, ranging from 1 to 50 Hz.  These can be identified using a spectrogram.  So my goal for the rest of my time out in Boise is to generate histrograms for these events.  I have many variables that can be generated, such as the timing of these events during the day, the timing of these events over the various months, and hopefully I can use the trends I see and match them up with the geothermal fluid logs taken from the lead geologist at Neal Hot Springs. Oh, and I will also have to begin working on that AGU Abstract!  It shouldn't be too extensive, but it will be beneficial to get something written so I have something to work with when choosing figures and designing my poster. Only a couple more updates to the blog, it's going well! Here's an example of spectograms for 9 Passive Seismic stations, over an 8 hour period.  As you can see at the 1:00 mark, there is an increase in amplitude where this event occurs with a frequency ~>1 Hz to ~20Hz.  This event most likely is a local event possibly caused by geothermal fluid flow!

2012-07-24T16:46:53-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_week_seven

I'm finally closing in on some figures that we might be able to analyze and get some interpretations and results. • Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o Go through the data and see what is good enough to use (sadly I think a large portion of the data will be rejected) o Use the good data for tomography to make a crude map of the velocity structure in Australia • UNIX o Learn about Illustrator o Comment o Learn the tomography code • GMT o Make new figures for analyzing whether the data is good enough to be used. New figures will include:  A map showing the path between the event and the station  The dispersion for that path  The raw seismogram from that path  A filtered version of that seismogram  The earthquake information (magnitude, location, date) • CPiS o Learn about sacmat96 so I can add useful commentary to the code o Learn how to make a dispersion curve for the PREM model • SAC o Make a nice bandpass filter to show the filtered seismogram • Understand what group velocity dispersion is used for and be able to communicate knowledgably about it o Read papers and thesis from someone at ANU concerning group velocity dispersion. • Be able to produce a poster which describes my project that is up to professional standards for AGU. o Select the good data from the new figures o Find a meaningful way to arrange the figures for the poster • Maintain this blog about what I have accomplished and my goals • Explore Canberra o I don’t think I’ll be taking and more weekend trips while I’m here but there seems to be quite a bit to do here in Canberra o Go see the National Dinosaur Museum and other attractions in Gold Creek Village o Go to the National Zoo and Aquarium o Go to the Old Bus Depot Markets 

2012-07-24T01:57:32-05:00 http://www.iris.edu/hq/internship/rss/interns/scarlet_seismology

Scarlet fever unfortunately made the last week a little shorter than expected and I was not able to get as much done as I was hoping. After a ride to the doctor and some antibiotics, I am ready to start playing a little bit of catch-up this week as the AGU abstract deadline is getting uncomfortably close! Before getting sick,  I was able to go to a DC summer classic "screen on the green" event showing Butch Cassidy and the Sundance Kid next to the Smithsonian! Related to my project, I was able to use illustrator to create some graphs of the parameters I have been talking about, and this week I hope to really get cranking on CCP stacking and analyzing it for the New Madrid area. I hope to have a bit more to share at the end of this week !

2012-07-23T17:34:50-05:00 http://www.iris.edu/hq/internship/rss/interns/week_7_picks_picks_and_more_picks

Well, sadly I don't have much to show for the work I've done over the past ~1.5-2 weeks, but I have been doing a lot!  I've been making picks of icequakes for my second timeframe, and although I felt like there were fewer icequakes, my advisor showed me a histogram that was just representative of picks on 1 station, and boy was I wrong!  Even when he produced the graph and I had an hour or hour and a half left of picks (out of 5 hours), I still had 3 times as many picks as I had in my last section!  It's been a very pick-intensive last two weeks, and I'm almost at the point where I can locate all of them at once (which goes much faster generally). Only 9 minutes left of picking!  But... for at least most of the rest of the day that's on hold because our system is being updated so I can't really get onto the computer.  (Same thing happened with that histogram...our system update was under way so I couldn't get a hold of it first.)  I'm in the library downstairs right now in order to write this.  So today I'll be working on catching up on some articles I've been meaning to read, and maybe starting to think about presentations and AGU abstracts and how to start those, even if I can't do all of it yet.

2012-07-20T14:56:00-05:00 http://www.iris.edu/hq/internship/rss/interns/week_seven

I can’t quite believe seven weeks of my internship are already done! I still have four weeks left, but I feel like the half waypoint of the summer just kind of flew by. Things have been pretty slow this week, though looking at my action plan for the rest of the summer, I know it’s sure to pick up by next week. Since you can’t remotely access the USGS server, unless you’re on a USGS laptop, I have to get all of my processing, interpretation and figure making done by the end of the summer. I’m not going to worry at all about my poster until I’m back at school in the fall. Abstract deadlines are also coming up, so I really want to get through a lot in the next two weeks to help add substance to my abstract. As I mentioned, this week was quite slow. I was picking the entire week essentially. I’ve never picked first arrivals before, so it was a pretty tedious week spent mostly going over my own mistakes. I finally got through all of my shots this morning, but now I’m just going through them again to make sure they all make sense as a consecutive series. Hopefully, then this afternoon, I’ll be able to learn a bit about the next step in processing- reciprocity. To improve and check the first picks, we use the basic physical fact that the time taken to travel between two points is the same, no matter which direction you come from. We can check the first picks for one shot by looking at the time it takes the energy to get from geophone A (the shot) to geophone B and compare it to the time it takes energy to get from the later shot at geophone B, back to geophone A. Hopefully, between that and killing any traces I couldn’t pick, I will weed out most of the bad picks (because there are a few!). In the meantime, I realized I never looked back at the goals I mentioned in the first two weeks. Now that the half way mark has come and gone, I decided it might be a good idea to go back briefly to some of my primary goals. “I know I’m going to be using a program called ProMax, as well as a lot of basic Unix so a large goal I have for myself is just to become comfortable and self-sufficient in both, given that I don’t have a strong programming background.” I’ve definitely worked on this one a lot and I feel a lot more comfortable with both Unix and ProMax. I’ve learned to find mistakes and fix them myself and I have a better grasp on what specific flows and codes mean. “On my final product, I know Adobe Illustrator and GMT will be involved so hopefully I can figure those out as well.” I haven’t touched Illustrator or GMT all summer, but I know I’m still going to have to. One of the guys in our office has codes in C that will create GMT scripts, plus Dulcie has been willing to let me look through some of her scripts to get a better grasp on GMT, so hopefully, I’ll be okay on that front. With Illustrator, this may be something I have to figure out when I’m at school and trying to throw together some maps for my poster. “I want to become more comfortable with doing fieldwork and learn to understand all of the little details that go into both planning and doing real fieldwork.” I think I’ve also had success with this one. We went out 4 or 5 days (and may be going out a bit more in August) and I’ve become familiar with all of the tools we use, what each instrument does, and how to take care of and install the instruments. Plus, for two of those days I was considered the PI, so I had the opportunity to put together and organize a field team, which was an interesting experience when everyone is years older than you! “I want to be able to understand how this kind of work can actually advance our understanding of seismic activity and fault hazards.” I haven’t gotten to interpretation yet, but looking through past papers and posters and making an action plan for the last few weeks, has helped me understand why we do each step in the processing. I’ve also gotten a better grasp, I think, on why the USGS does this and what results they get from these surveys that they deem worthy of being released to the public.  

2012-07-20T13:50:12-05:00 http://www.iris.edu/hq/internship/rss/interns/baby_got_backazimuth

This week I've been steadily chugging along, picking events in SplitLab.  I've finally finished the A stations, which run down the central part of the Ruby Mountains.  It's pretty mind-numbing work, to be honest, but I've been listening to lots of NPR podcasts and a Bill Bryson audiobook, which help.  Now I'm working on the D stations, which are scattered around the periphery of the area and were operating for only a few months, so they should go quickly.  I only set aside one more week for picking, so with only about one-third of the stations done, I'll have to chose a representative sample of the remaining stations in order to get good coverage. So I'm noticing a problem in terms of the locations of useable events.  In order to see the SKS phase, I can only use events with a magnitude of greater than 5.5, and a distance of 90-130˚ from my stations.  Unfortunately, the vast majority of earthquakes fitting these criteria are located near Indonesia, and sometimes Papua New Guinea.  So I've got really great coverage at a backazimuth of around 270˚, but virtually nothing between 0 and 180˚.  In fact, only one station (A14) has a somewhat-relevant point from this direction. This image isn't the most intuitive, so I'll take a moment to explain it (it took me a while to fully understand all of it).  It's centered at the station, with each small blue line representing one of the points I have picked.  Each event is plotted according to its backazimuth and distance to the station, while the angle of each line from 0˚ represents the fast-axis splitting direction.  The length of the line is proportional to ∂t, the time difference between fast and slow axes.  Red circles represent null events, in which backazimuth is either parallel or perpendicular to the fast axis.  This particular station was exciting, because it can be seen that there is a point with a backazimuth in this "shadow" area where I haven't gotten many points (139.54˚, to be exact).  It's not necessarily a very good data point--notice how much larger the splitting time is than for the other points, which makes me suspicious--but it's reassuring that it appears to be yielding a splitting direction similar to the other points. Last Saturday I went with some other interns from various Stanford programs to Hollister, California, which is about an hour or so south of Palo Alto.  It's near the area where the San Andreas Fault splinters a bit, with the main portion of the SAF stepping to the West, and the Calaveras Fault (and later, the overdue-to-rupture Hayward Fault) splitting off to the East; it is between these 2 systems that the San Francisco Bay lies.  Anyway, Hollister lies directly above the Calaveras, which is currently slowly and steadily creeping.  This is in contrast to the stick-slip model of motion, which is associated with strain buildup and sudden earthquakes.  So Hollister doesn't experience large earthquakes, but everywhere there is evidence of the fault slowly chugging along:  Here, a cracked curb clearly shows the right-lateral motion of the plate.  And here, a sidewalk and concrete fence are in constant need of repair.  It's a small price to pay when you consider that Hollister residents don't live in fear of another large earthquake like many Californians. And finally, we stopped at the mission at San Juan Bautista on our way back into town.  I learned that El Camino Real, a major road that goes along the Peninsula, which I live a block away from, was originally the name of the road connecting the Spanish missions in California, spanning almost the entire state.

2012-07-20T12:27:35-05:00 http://www.iris.edu/hq/internship/rss/interns/overcoming_the_final_leg

Hi World! So this is my last week in Oxford before I leave to Penn State :’(, but I’ll still continue to work on the project throughout my stay there and the school year because I want to make my mark in the scientific community. These past few weeks I’ve been comparing my data with my mentors data and learned a new feature on SAC that actually helped me out 10x’s better than actually making my picks one by one with 4 different events. This feature is called relative plotting or p1 rel/p1 r. It actually aligns the seismograms from a receiver station that you choose to view according to which ever pick you desire, but this is accompanied with the feature xlim, which puts limitations by your desire on how many seconds of the seismogram you want to view out from the pick of your choice. Sounds complicated? Nooo, that’s the easy part. The hard part was trying to homogenize my own data so I can see some type of trend then compare it to other maps to see if they appear to be similar. This called for (literally) over a thousand commands of chmod +x (to renew my maps) and map.sta.csh 1, 2, 3, 4….. lets just say I’m glad I’m almost done. The tricky part about homogenizing the trends of these maps was that a slight misalignment of the SsPmp picks on the seismogram and the trends on your maps off of the same station would look foreign from each other. In some instances I had stations that wouldn’t show at all, like really, one station totally disappeared. After I finished the homogenization I then began to compare my data to Mike’s and luckily the appeared to be somewhat similar to each other. (Another note, I learned the difference in Amplitude in a seismogram could make a huge difference in comparisons). Now all I’m waiting for is the program that will help me convert these time arrivals to actual depths so we can get a profile view of the actual structure of the Eastern U.S. I’m so excited! This study can go so many different ways and I’m just glad to be the person that contributed to this fairly young study in the Eastern U.S. I’ve began writing my paper and I pretty much have my abstract already mapped out, all I need is my final figure and I’m done. As for life these past couple of weeks, Noor held two gatherings at her house, Burrito night and Megan’s (her close friend) Birthday. I loved both events and the company from Jared (freaking hilarious) , Yi (most friendly person I know…. In life), Sarah, Katie, and her boyfriend Scott (he’s a cool dude). Oh! And Noor just pointed it out to me the other day that her shirt was missing…. See facebook and social networking for me is not my key strength, I’m old school, just call or text me lol. On a good note, we’re taking pictures tomorrow with the shirts on and I’m going to post it on my next blog. I can’t wait to see you all (IRIS Interns) at AGU, its going to be fun! Well that’s about it for me, and Noor if I forgot something that we did please comment and let me know, also world, if you have any questions comment me, email me @ Saro357@yahoo.com or CalvinJohnson357@gmail.com. Also! I’m starting a paper because I want to work towards getting it published! An update on the USArray won’t hurt the society. Thank you all for reading and God bless, Sincerely, Calvin E. Johnson  

2012-07-20T01:29:26-05:00 http://www.iris.edu/hq/internship/rss/interns/week_7_-_five_cake_fridays_to_go

July 16 to July 20 On Wednesday at tea one of my friends asked me how long I had left here, and I said 5 and half weeks to which he responded, “Good! Six more Cake Fridays!” I think that’s a good way to summarize how I feel about my time left here, it’s short but there’s a lot left to look forward to! There’s also a lot left to do. I’ll be both happy to go home and sad to leave, but right now my main worry is not accomplishing enough before I go. Today was a good Cake Friday, a nice chocolate cake topped with Smarties (they’re like m+ms, we have them in Canada but in the States you can usually only find them in the foreign foods section). So now I have only five Cake Fridays left! In my work right now I have processed the data from my six events and I have all the dispersion curves from that, ones for each station and ones showing all the stations. I updated the codes to plot the two different filters on the same page for each separate station and to have different colors and a legend for all the stations together. I’m learning a lot about GMT, and soon I hope to post a map that has all my events and lines connecting to all the stations where data was gathered. I probably don’t have enough data to do tomography and make a map, but we’ll see. I still need to find out if the way I’m processing the data is appropriate though and I’m assuming I’m going to have to change some things in the code before I can really produce any final pictures. The next big thing for me to do is to find or make the dispersion curves for the PREM model and add those to my plots. It will be good to have something to compare my data to. I think I may also add plots of the seismograms to the individual dispersion curves, so I can see which curves we can clearly see the surface waves and which ones look mostly like noise. I’ve been catching up on reading people’s blogs, it’s good to finally catch up a bit on what people are working on, and see that frustrations with coding are not uncommon. Fortunately for the most part I find the coding to be more interesting than frustrating, even when it isn’t working. I definitely surprised myself with how much I like it! Here are some of my plots for the March 23, 2012 event.         On a side note, it’s my mom’s birthday today! Happy Birthday Mom! Cheers!  

2012-07-19T21:35:24-05:00 http://www.iris.edu/hq/internship/rss/interns/first_gmt_figure_and_looking_forward

Thankfully, I think I am finally getting closer to having sorted through all of the necessary data to start getting interpretations. "Close" is definitely relative, but I feel closer to the end of it than the start now! After cross-correlating about one and a half more fault segments I will just need to finish picking my arrivals to calculate locations and the initial results! On Tuesday I produced my first GMT figure, which is simply a fault map overlain by the station map used for my project. Fortunately I don't think many of the figures I will need to produce will be too much more complicated than this one, but that remains to be seen. The weather is finally cooling off here. It rained almost all of last night and was about 71 degrees for my bike ride to work. After checking the temperatures for the last month I can confidently say that it has been over 3 weeks, maybe even more, since it has been that cool in the morning. Hopefully this will last a while. Back to picking arrivals!   Cheers! Ryan

2012-07-19T09:51:41-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_6.0

I actually can’t believe that I’m more than half way done now. I had to count the days to double check! The time has flown by so far and I think it’s only going to go faster. Here’s the updated goals list. • Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o Create all the dispersion curves for all six events! o Figure out if the differentiation step in the code is appropriate for my data. • UNIX o Learn about Illustrator? o Comment my codes! I want them to be comprehensible to other people and to myself in six months when I’ve forgotten all the specifics. • GMT o I’ve been doing a lot of GMT practice recently, making my dispersion curve figures. I do have a GMT helper code, and I should add more information to that. • CPiS o Learn about sacmat96 so I can add useful commentary to the code. • SAC o Comment in the code what SAC is doing and how we use it. • Understand what group velocity dispersion is used for and be able to communicate knowledgably about it. o Read papers and thesis from someone at ANU concerning group velocity dispersion. • Be able to produce a poster which describes my project that is up to professional standards for AGU. o Find PREM model to compare my dispersion curves to. o Find other maps to compare my data to. o Find a nice way to arrange all my figures so they can be interpreted in a meaningful way. • Maintain this blog about what I have accomplished and my goals. o Get back on schedule with blog posts – almost there! • Explore Australia! o Consider going to Melbourne for a weekend? 

2012-07-19T01:31:59-05:00 http://www.iris.edu/hq/internship/rss/interns/hello_again_world

Sorry I haven’t posted in a while! I took the week off to head home for the 4th of July and am working to get back into the swing of things. It was a very nice, relaxing week with lots of good food, company, swimming and sun. Last week back at work, I read more thoroughly through a few papers, which analyze electromagnetic data and conclude they see precursor anomalies, in order to come up with a list of processes they did to replicate on our data. The first analysis I am going to focus on is looking for a certain type of pulsation characterized in Bleier et al. 2009. What I understand so far is that the pulsations are characterized by having amplitudes greater than twice the site background noise, are unique in duration (1-30 seconds) and exhibit strange singular polarities and bi-polar waveforms. I am going to look in our data for pulses like this. End of last week and this week I have been figuring out how to download my raw data and filter it. Caroline, another intern in my lab, taught me the basics of SAC in order to determine the time a bunch of earthquakes (chosen using my earthquake graph shown above) arrived at our stations so that I would know where to look in our EM data. I had to use some filters on the seismic data to see the arrivals more clearly. I figured out how to use what is called a bandpass butterworth filter. The code I type in SAC is “bandpass butter corner 0.33 10”, where “corner” and the numbers indicate the range of frequencies I want to KEEP with my data. I am very entertained every time I type butter! I also figured out how to open our raw EM data in MATLAB and have written a bandpass butterworth filter in MATLAB to filter our EM data in the same way as the seismic data because the frequency of the seismic and EM data are about the same. Simon also has me beginning to write up and organize my abstract and things that will go on my poster for AGU, like an introduction, any background and graphs I think I will have. This is making me realize that I am halfway through my internship, which is pretty intense! Since I haven’t produced any concrete graph or results recently I having been feeling slightly like I am not moving forward, but when I take a step back, like I did when writing this blog post, it makes me realize how many different things I have been working on to get me ready to produce actual graphs and results. I’m excited to see what I find!

2012-07-18T01:27:03-05:00 http://www.iris.edu/hq/internship/rss/interns/week_6_-_where_did_it_go

July 9 to July 13 I somehow barely noticed that week going by. I got back Monday night (the 9th) from Sydney and my brother was still here with me for another week. So between a 4 day work week and having my brother around the week just went by so fast! In fact it went so fast that the homework deadline really snuck up on me. Fortunately I keep a master to do list on my computer so I didn’t forget entirely. I kept meaning to work on the homework while I was at work and then forgetting because there was more code and debugging to do. I spent some time modifying the big code so that the naming conventions and variables are more suited to my data. It was written for ambient noise data and I’m using earthquake data so there were quite a few changes to make. Everything seems to be up and running now, the next step is modifying my scripts that make images of the dispersion curves so they are nicer images and possibly include the calculated dispersion for the PREM or other models. The dispersion curves will be most useful if we can also compare them to dispersions that other people creating maps of Australia computed. My adviser is working on getting those maps and dispersion curves for us. The time in Sydney was wonderful and I’m going to miss having my brother here. I can’t believe I have less than six weeks left, it’s weird how fast the time has gone already and it’s only going to get faster. I hope I have something to write an abstract about soon! I do have lots of figures now though! Here is a map of an event I use and the stations that I took data from. The event occurred on March 23, 2012 and was magnitude 5.7. You can see a place where there are a lot of stations all in a small area. I think looking at those curves could provide a good estimate for error or at least some sort of maximum difference calculation. Here are some of the dispersion curves from that event. This is the curve from QLP, one of the stations closer to the event.  And this is a plot of the dispersion curves from all the stations that I gathered data from. I think I’d also like to look at dispersion as a function of azimuth if there is time. Hopefully next week I’ll have some more figures to post, especially these figures with the PREM model dispersion curve added. One other thing I do need to do more is read everyone else’s blogs, and send some post-cards. I stocked up on postcards in Sydney, now I just need to write them and get some stamps. Till next time!  

2012-07-17T19:00:43-05:00 http://www.iris.edu/hq/internship/rss/interns/three_weeks_to_go

With three weeks left in my internship, I think it's time to begin reflecting on the goals I made for myself at the beginning of this internship. Overall, I would like to develop a greater understanding of geophysical concepts and how these concepts can be applied to solve problems. -  I hope to gain experience with Unix as well as Antelope and understand the codes and commands that will help me interpret the large amounts of data given to me. This is definitely a goal that I have accomplished.  I have become familiar with navigating through large amounts of data using Unix and Antelope, and I definitely hope that I can apply this computer programming experience to future ventures in geology/geophysics. - Develop an understanding of geophysical techniques used in the field, specifically at the Neal Hot Springs geothermal plant. At Neal Hot Springs, I have gained the experience of accessing and servicing many seismic stations around the geothermal plant.  I pretty much have the service sheet process memorized!  I have also taken part in acquiring paleomagnetic and magnetic data using different geophysical tools that are extremely useful in understanding the local earth structure.  - I hope to analyze the data from the field to come up with valid interpretations about the processes that may be occurring, in order to prepare an abstract and poster for the AGU conference in December. Because my project took a slightly different direction than what was originally planned (microseismicity to receiver functions), my new project involved working with a process that was even new to my advisors!  Although I have read and learned about the receiver function process, how it can be applied in the field, as well as the hoped-for results, with three weeks left it has been frustrating to not be able to produce sufficient receiver functions*.  Although presenting a poster at AGU was my end goal, and it still is, it's somewhat frustrating to think that I may not be able to acquire valid data to come up with any sort of interpretation.   - Lastly I hope to explore all of what Boise has to offer, from the ample coffee shops to the bike trails along the Boise River! I have definitely tried many of the coffee shops in the Boise area, as well as haven taken advantage of the Boise Green Belt, a 20+ mile bike/footpath along the Boise River.   * Last Friday, it became apparent that the gain settings on our seismometers out at Neal for each of the components, N,E, and Z were all mixed up.  Some gains were at a factor of 32, while other gains were at a factor of 1.  This creates problems when analyzing unnormalized data for receiver functions, because for some stations, the vertical-component amplitude was at a much higher gain setting than the two horizontal component amplitudes.  Rotating this unnormalized data proved to be difficult when having to use different gain settings. 3 of us went out into the field yesterday to fix these gain settings for the future data sets, but for the data sets that I hoped to use, the gain settings obviously could not be adjusted in the field.  Hopefully we can adjust these settings using code, but the question of whether these gain settings actually affects the receiver function application also arises.  Because in the deconvolution process, the Impulse response of the seismometer is cancelled out of the equation when isolating only the earth response.  This week, we'll troubleshoot these receiver functions, almost as a last-ditch effort to see if we can produce anything.  What's even more frustrating is that even when we shipped our data off to another receiver function resource to see what they produce, similar, bad receiver functions result, as shown in the image below. Hopefully we can produce something significant, but filling that AGU poster with no interpretation of good data is really starting to haunt me...

2012-07-17T12:21:29-05:00 http://www.iris.edu/hq/internship/rss/interns/week_four_field_work

This week has been a whirlwind of activity here. We have been working surveying the line along which the stations will be placed later. We have a team of eight working everyday. The line, as can be seen in the picture stretches from eastern Oregon to western Idaho. The stations are placed with such spacing that we will be able to see all the way down to the Moho. This resolution of imaging will allow Virginia Tech to look at the base and source of the Idaho batholith. The Western Idaho Shear Zone has been proposed to have a vertical offset, where the lithospheric portion is further west than the crustal portion. This is a conclusion that has been gained by looking the sharp strontium isotope gradient that occurs at this boundary. One of the goals of the IDOR project is to get a look at the structures beneath the surface at the Salmon River Suture Zone to see if we can observe this offset.

2012-07-17T00:55:48-05:00 http://www.iris.edu/hq/internship/rss/interns/to_sleep_--_perchance_to_dream

I dreamt about Fortran 77 and HASH last night. The dream was a half-asleep train of thoughts about worrying that the program might not work, and then another part of me attempting to assuage the worried part of me. I'm pretty sure the line "Don't worry, just remember to edit the format of the first entry to fivev characters and note that in the driver" blearily ran through my head as I tossed around on an air mattress. This train of thought was finally interrupted by me blearily waking up at 4 am, whereupon I remembered that I was in fact not at work, but rather visiting a friend in San Diego. It's a shame; couldn't I have dreamt up some genius insight instead of worrying? Instead, my subconscious decided to grace me with a checklist of things-to-do.  My life this past week has pretty much been comprised of writing, debugging, and thoroughly checking Perl scripts that'll format my text files for me. I adore Perl; it has a module for everything tedious and basic, so I didn't have to do any nasty time manipulation or irritating decimal latitude to degree/minute/second latitude. My regular expressions have been messing up somewhere, but there are so many other ways to code in Perl that I just didn't need to use them. Yay! I then was able to tease out some understanding of the HASH code, which makes me considerably more relieved. I rather dislike using black boxes, so I'm glad that I at least understand the structure of the code now. It makes me feel considerably more at ease. In other news, it turns out that all the data from all the seismograms were acausally filtered. One of my mentors, Danielle, went through and filtered them in SAC, and then converted them back to Antelope -- a bit of an ordeal, especially considering that she was on a research cruise off the coast of Oregon for the last leg. So now it looks like that I'll be going through and adjusting the picks. Good times. More Antelope! It rained for the first time this summer in SoCal. I was impressed. Quite novel.

2012-07-16T12:51:23-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_revisited1

I figure with 3 weeks left of my internship it’s time to take a look at the goals I made at the beginning of the summer. One of my main concerns my first week in St. Louis was my lack of programming experience. While I’m definitely no expert, I’m far from the novice I was back in June. Although there are still times when I need help, I’m now able to troubleshoot many problems on my own before asking for help. It’s quite encouraging to think of how much I’ve improved! Another one of my goals was to become more adept at examining seismograms. In the past few weeks, I’ve become much better at recognizing the characteristic patterns that indicate “earthquake” and those that might be tremor (I’ll show some figures of what I’m talking about later in the week). Much of my summer has been thinking about life after I graduate from PLU this coming May: graduate school. I haven’t quite figured out what area of the geosciences I want to be in, but there’s still a little time left to figure that out. Katie, our alumni mentor, gave an awesome presentation during the orientation week. She suggested thinking about where I’d want to be geographically, so I’m looking at schools in the Pacific Northwest, primarily. By the end of the summer I want to have a clear plan of the schools and specific programs to which I’ll be applying. That’s all for now!

2012-07-16T12:28:56-05:00 http://www.iris.edu/hq/internship/rss/interns/less_than_a_month_left

I only have about a month left in my internship. It’s going by really quickly. My last few weeks are pretty clearly mapped out. I hope to be finished picking earth quakes in the next two or three weeks and then in my final two weeks, I’ll spend my time working on my abstract, poster, and a professional paper. I think the final couple of weeks will be really interesting and at this point I just have to make one final push to get through the rest of the data. I’m a little nervous about putting together the results from the project. I still don’t know exactly what we can say about all of the earthquakes that we have located. Luckily, I know that I’ll have lots of help when it comes to that part of the project, and I’m sure we’ll be able to produce a great finished product to present at AGU. AGU should be interesting. I’ll potentially be presenting one poster for my IRIS project and one for my senior thesis project at New Mexico Tech. I’m also really looking forward to reuniting with all of my new friends from the IRIS program. Ok, time to get back to work. I want to finish picking earthquakes and start looking at results ASAP!  

2012-07-16T11:28:54-05:00 http://www.iris.edu/hq/internship/rss/interns/week_42

This past week I have been out in the wilderness of Oregon and Idaho enjoying the outdoors while working on the IDOR project. The aim of this project is to use active source seismology to gather data that will be used to create a tomography model . This model will be used to understand the different layers in the Earth's crust and other geological features. This is similar to what I am doing with the SSIP data from line three.   The picture above is part of the line in Idaho. I am working with a crew of eight students ranging from graduate students to undergraduates from all over the country. Each day we split into teams of two and survey a portion of the IDOR line. (Unlike SSIP that had multiple lines, IDOR consists of one long line) When surveying we locate predetermined sites with a Garmin (GPS) and pick a suitable area for a seismometer to be buried. We then label the spot with a numbered wooden stake and record the location using a Trimble (GPS). In August, the deployment team will locate our stakes and set up the appropriate seismometer. The picture above shows the four survey vehicles. Each day has been an adventure. Our goal is about one hundred stakes per team per day, so our pace is often fast. However there has been many  twists and turns along the way. The crew has experienced three flat tires, a rattle snake, and a black bear. Thankfully we have all made it out safe and now know how to replace a flat tire in less than ten minutes.   Besides picking up useful tire changing skills, we have had the opportunity to explore the local geology. We have been able to climb on outcrops and have even seen several igneous dikes. So far the team has collected several pounds of igneous and metamorphic rocks from these outcrops. This collection includes several pieces of obsidian. This leads me to my next topic. Flint knapping!!! I have been trained in flint knapping, so I felt it was a great opportunity to share my knowledge with some of my fellow crew people. Without handmade tools, we had to use a rock as a tool. I was not successful in passing my skills along, but I was able to make a few little arrow heads. The picture above shows some of the larger pieces of obsidian before they were thinned and a pile of flakes already taken off. The picture above shows some of the worked on pieces. The picture above shows my most successful attempt at an arrow head without using handmade tools. This has been a fun week full of hands on field work and hands on geology lessons from the other crew members that have geology degrees. I have been really grateful for all the geology knowledge I have been exposed to because my Physics coursework has not allowed me much time for geology courses. Stay tuned next week to find out what wild animals have crossed my path and what new geologic features I have explored. Goodbye for now. Sincerely, Amanda

2012-07-16T09:59:20-05:00 http://www.iris.edu/hq/internship/rss/interns/receiver_functions_with_albert

I spent this week running the matlab code for receiver function parameters. It has taken me much longer than predicted. Unfortunately, I have been having problems creating illustrator plots, but resolving this problem will be part of my goals for next week. While the codes have been running I have taken the time to write up the general goal of this part of my project as well as what changing each parameter does.  The basic idea is that to get good receiver functions that can be most easily interpreted requires knowledge of the parameters that can be changed and how changing each parameter will affect the data. When changing parameters the goal is to minimize the noise without changing the integrity of the deconvolution. For the parameter changes, only the parameters being tested will change and all other variables will remain as constants. There have been three stations chosen to undergo parameter changes. The first is CBKS, which is a permanent US station located in Cedar Bluff, Kansas. This station has been active for 17 years and therefore has a lot of data to offer. Underneath the station lies basement geology of consolidated sediments. The second station is MPH from the New Madrid (NM) seismic network and is located in Memphis, Tennessee. This station has been collecting data since 1998, and unlike the US station CBKS it lays on unconsolidated sediments along the Realfoot rift. The final station is V42A of the Transportable Array (TA) network and has only been around since 2011, so it has not collected much data. Like the NM station MPH, it also lies on unconsolidated sediments around the Realfoot rift.  The goal is to compare each station with itself as different parameters are changed as well as to compare the receiver functions of each station against one another. Things to consider about the stations when they are being compared to each other include the length of time the station has been active and the geology underneath each station. After all of this has been analyzed, the next task is to determine the minimum magnitude event that can still provide a significant number of viable seismograms for each station.   Like Greg mentioned in his blog, I’m really glad that there are so many good papers on receiver functions. Although I was getting bored of reading papers at the beginning, it has really helped to gain a background in receiver functions and it’s exciting to know exactly where to look when you aren’t sure about something. On that note, I’m going to take the rest of this wonderful Sunday afternoon to go read about the crustal structure along the North Anatolian Fault zone with Albert  down the street!  Al's such a great listener!   Until Next Week !  

2012-07-15T13:03:50-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_the_fifth

I’m running late on my blog posts, the trip to Sydney kind of threw everything off for a bit but I’m slowly getting back to my usual schedule. This week was short but fairly productive. • Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o So far I have gathered data from six earthquakes, magnitude five and above, that occurred on the land in Australia o I need to go through that data and create the dispersion curves, maps of the event and seismometers (hopefully adding lines between the event and each of the seismometers), and then see what the next steps are • UNIX o I finished two different codes to plot the seismograms, one that plots each one separately and one that plots them all on the same plot in different colors. o I want to learn how to make those figures nicer, adding legends and making a nice layout for all the separate ones. o Keep learning about the codes I’m using – avoid the black box! o Comment the codes I use frequently. • GMT o I would like to update the code I have that plots the earthquake and the seismometers used to create dispersion curves so that it plots the great circle path between the earthquake and each of the seismometers. I would also like it to automatically adjust the window of the graph to include all stations I used. • CPiS o One of the codes I use calls sacmat96 and I would like to know what that program actually does. • SAC o I don’t have any specific goals concerning SAC now but I would like to keep learning about it. • Understand what group velocity dispersion is used for and be able to communicate knowledgably about it. o Read papers and thesis from someone at ANU concerning the group velocity dispersion. • Be able to produce a poster which describes my project that is up to professional standards for AGU. o Make the dispersion curves for all six events, then start contemplating the abstract. o Find PREM model to compare my dispersion curves to. o Find other maps to compare my data to. • Maintain this blog about what I have accomplished and my goals. o Get back on schedule with blog posts. o Include more figures from my work. • Explore Australia! o Consider going to Melbourne for a weekend?  

2012-07-14T00:03:36-05:00 http://www.iris.edu/hq/internship/rss/interns/week_6

This week I’ve continued with the (pre) processing of my data set and I’m finally starting to get the hang on using the Vi editor and ProMax. I’ll admit the week did get off kind of slowly and I ran into a few problems, mostly caused by my own carelessness. On Monday, we had a power outage and then the madmax server (which we need to get onto ProMax) went down and so I have to wait a few hours for that to get rebooted. I did spend some of the time talking to my advisor though about creating a working plan, now that the preprocessing is finishing up, of things that I want to do to the data and what I hope to get out of it. I’ve been going through a few more of my advisor’s papers and papers published by the team here, as well as AGU abstracts they’ve written, to get a sense of the usual processing steps. It first involves getting through the pre-processing and then through first break picking, but from there I will have to migrate and stack the data, use reciprocity to make up for bad and skipped shots, and possibly use deconvolution to improve the resolution of my images. I think I understand all of the concepts fairly well, but we’ll see how it goes when I actually have to start applying them using ProMax flows! It was useful though to get a sense of what I need to get done in the next five weeks, and also start thinking about what kind of images and what texts I’m going to want on my poster. Finally I was able to get back onto madmax and learn the next few pre-processing steps. On Tuesday, I ran into a wall when one of the flows kept freezing on me, but it was soon pointed out to me that the file I was trying to import was merely empty (the program I used had malfunctioned and not copied anything to the file). Then I kept getting erros on another flow, but soon realized it was only because I was using the wrong instrument number. And then of course, I spent a while looking at the output file of one of the flows responsible for removing repeated shots, before remembering that I didn’t have any repeated shots and that the output file was supposed to be essentially empty. Those little silly mistakes have been a lot of what have been slowly me down, but once I got through those, I was able to get the fake geometry all set up on ProMax and then get rid of any bad shots from my data. Technically, once the fake geomeotry was done and the necessary files were imported onto the system, I was supposed to upload the real geometry that is based on the actual coordinates of the geophones. But since I haven’t gotten that file yet from our GPS guy, I had to upload a new ‘less’ fake geometry. It still uses the spacing between the geophones as the coordinates, but this time it bases the geometry on all 118 stations, rather than a standard 60 stations. I had to then go through all of the same uploading and set up steps from before, and this time run a flow that combined and resorted the data from both RXs together. At that point, I needed to artificially move up every shot to the same time to compensate for any variations in shooting. To do this I just had to run a few more flows and ProMax code to create a spread sheet of the amount of time each shot needed to be shifted (we wanted every shot to be as if it had taken place at 2ms). I then had to read this spreadsheet onto ProMax so it would shift all the shots. In the same flow, I was also able to kill all of the bad traces I had found previously. This flow also did automatic first break picks on the trace each shot originated from. With this I could make sure that the first picks looked good, that the polarity (the direction the geophones were facing) of the traces were all the same, and make sure the shot was recorded at the correct geophone. Once all of these checks had been done and the shots had been shifted, I was able to begin the next flow- first break picking. I have quite a lot of shots and my data is quite noisy, but hopefully I’ll be able to have picked all my first breaks for the P-wave line by early next week. Of course I ran into lots of little problems along the way, but it’s amazing how much better I’ve become at actually identifying and solving the problems myself. I’m also a lot better at understanding what the actual issue is when someone points out a problem to me. So it’s still slow going, but I would say I’ve definitely made progress!    

2012-07-13T13:59:00-05:00 http://www.iris.edu/hq/internship/rss/interns/the_midway_point

Well, this week I officially reached my half way point for the internship. (half way through the week).  Last week I reflected on some of my goals from the beginning, but now I'm going to reevaluate them and determine what old goals to keep and new ones to go on the list! So here are some things I've got: continue hiking and get out in the field maybe 1 more time continue to read more of the icequake literature to help me with my analysis that'll come up soon finish my second round of icequake picks (2 hours out of 5 down this week thus far, and I still have today!) continue to use matlab as a tool--this includes coming up with more good ways to compare my two time periods in a reasonable way presentation preparedness:  I'm going to include my AGU abstract as well as the talk I'm giving here during my last week in this section figure out what I'm doing for my senior thesis Some old things on my list that I've accomplished: learn more about glaciers and seismology use matlab as a tool use time-lapse photography for science field experience hiking getting to go to Alaska! Learing how to live on my own, not in a dorm Now for some of my progress from this past week! I mentioned last time that I was going through and determining a new time period.  I'll did pick a period and have started my picks for that time, and I'll show you how I got to that point!  But first, I'll give you a couple of cool figures that helped wrap up my last time period. Here's all five hours (6:29-11:29 UTC, aka 10:29 pm-3:29 am AK time).  The fuschia colored icequakes should be easier to see now! We then added some error ellipses, which can give you a headache if you look at all of them at once. (As you can see below).  There are definitely some crazy ones, I'll admit, so that's why I'm going back and looking at those events to try to see what in earth is going on!  But in the second figure below this one, I've chosen a shorter time period to look at so maybe we can actually understand the ellipses and their importance. When we have a feature where the ellipses’ long axes are perpendicular to the feature, we are more convinced that it could be an actual feature. On the other hand, if the long axes of the ellipses are in parallel with the feature, it is harder to convince yourself that it is actually a feature, and you might conclude that it is possible all of the points occurred at one location.  So if we look at the medium-sized ellipses stacked on one another on the right side, that linear alignment can actually be a feature.  On the other hand, the tight cluster on the left where the ellipses line up with the feature, we find it less convincing the nature of that feature. Also, we're starting to think about looking for patterns for automatic detection.  Below I've just included some of the stacks, which pulled out just some of the most common patterns, and it tells you how many there are in that subgroup of similar waveforms.  These stacks are looking at individual stations.  On the left you have our station CNTR, while on the right is station LINC.   To find my new time, I started looking at the beginning of my first group, and started looking at my precipitation, temperature and wind for the week following.  We therefore have a consistent amount of influence from preciptation (We have no precipitation during this time period).  Our next idea was to look for sunny periods in the middle of the day for contrast, and preferably within a few days, so we narrowed down the search further.  I calcualated some times that I would consider the middle of the day with the most sun cover.  I determined to look at a time between 11 am and 4 pm AK time (19:00-00:00 UTC).  The results narrowed down to a few days can be seen in the second set of graphs below.  It has a few times marked off by colors on each end of the time period.  The back markers represent our control period.  The other colors represent potential time perods.  Along the bottom of each graph, the format is: day, hour.  I ended up looking at time-lapse videos over eachof those time periods to determine which time period had the clearest sky.  The first one marked in magenta had very clear skies and therefore presents the best contrast to the control period. I've made lots of progress with my picking in this time period, and will hopefully finish up the picks by mid week next week. Until next time!  Let me know if you have questions.

2012-07-13T13:40:25-05:00 http://www.iris.edu/hq/internship/rss/interns/halfway_there

So last weekend marked the official halfway point of my internship (!). I realized I never really acknowledged that in my blog post last week, though I did speak with Simon and Mairi to outline a more definite timeline for the rest of my time in Palo Alto. So in honor of this occasion, I’ll spend some time looking over the goals I set in the beginning of June:   1. Improve knowledge of seismic methodry: how sensors work, how data is collected and interpreted.
 I got to work with the sensors and the data acquisition a little bit when we were out in Nevada. I can’t pretend that I understand all the electrical complexities of the equipment, but I know the basic components of the stations, and I can now download data from the SOD database.  2. Gain facility with seismic data interpretation and the necessary software (related: improve computing skills, especially in UNIX and programs like GMT)
 I’m definitely waaayy better with SplitLab now. I’ve written a few scripts in UNIX, and though I don’t use Matlab too much outside of SplitLab, I’ve brushed up my skills just by helping some of the other interns with their codes. 3. Learn to connect seismic data to real features; in particular, to relate anisotropy to physical structures.
 Haven’t done much with regards to this area, but I’m planning to spend a lot more time focusing on the geological interpretation during August. 4. Talk with professors and grad students, and become more comfortable interacting with people in an academic, professional environment.
 I’ve gone to a few events, and I met a lot of people when I first arrived. However, I’ve noticed that once I settle into a new workplace and get to know the people immediately around me, I’m not that good at branching out and meeting other people. So I’m still going to work on this one. 5. Construct a plan for after graduation next year. This part might involve researching grad schools and/or taking the GRE, even if it seems intimidating right now.
 Well, I signed up for the GRE and spent a little time last weekend looking at some potential schools/advisors. This is something I can continue to chip away at over the next month. 6. Enjoy spending the summer at Stanford! I've never spent more than a week or two at a time on the West Coast and I want to get the full California experience. Some things I want to try: surfing, In-N-Out Burger, and buying/cooking lots of local products. From biking around, I’ve gotten pretty familiar with Palo Alto and with Stanford (a nontrivial task, considering how huge the campus is). I haven’t been surfing, but I did go boogie-boarding, and I did have In-N-Out Burger (I approve!). There’s a nice farmer’s market on California Avenue, very close to my apartment, that I checked out last weekend. I’m planning on getting produce from there more, since Trader Joe’s though overall a wonderful place, has less of a fresh produce selection than I’d expected. So that’s a pretty good summary of both how my summer has gone, and what I can expect for the next month. This week, my work has gone slower than I’d hoped. The UNIX code that I’ve been using to rename and sort my data files—to make them more SplitLab-friendly—was giving me a lot of problems on Monday. Alex, the other intern in my lab who is using SplitLab, showed me how to re-order the data so that I didn’t have to do any re-formatting. He also showed me how to make sure the components were all of the same time span, which solved another problem I’d been having. So I ended up just re-ordering all of my data. When I finally started to go through the stations, I realized I have way more events than anticipated—sometimes over 300 per station! I mentioned earlier that I’d constructed a rough timeline? Well in that I had assumed I could finish 2 stations per day; it doesn’t look like that’s going to be possible, unless I can improve my speed considerably. Mairi told me not to worry, that I could finish the work even after I return to New York in the fall (thank goodness for ssh –Y!) In addition, one of the grad students tinkered with the SplitLab code to produce a nice colorful map of the anisotropy parameters. This is so that we can stack all the results for a single station and hopefully reduce the error due to noise. It was cool to see the process first-hand of a student reading about a technique in a paper and deciding to implement it. Plus, it produces really cool-looking images: This weekend I’m going on a field trip sponsored by the School of Earth Sciences to Hollister to see the San Andreas Fault. There’s a lot of slow-slip faulting there, and it should be interesting to see firsthand. I’ll post pictures next week!  

2012-07-13T11:27:31-05:00 http://www.iris.edu/hq/internship/rss/interns/week_three1

Over the weekend of June 30th Virginia was hit with several severe storms and tornadoes that wiped out power lines, cell phone towers and trees like the one pictured below.  Blacksburg was lucky for the most part. Only one section of the town lost power and it was restored relatively quickly compared to the surrounding areas that are still without power. Pictured above is a pine tree near Virginia Tech campus that fell down during high wind storms. We were fortunate enough to have power on Monday in time for work, so there were no delays in data processing. This was important because my week was spent trying to fine tune my tomography model before we had to leave for Idaho to work on the IDOR project. The first part of my week was spent developing a velocity model based on line three data. This was used to replace the velocity model that was based on line one data, which was used in my first tomography model. This was done in order to produce a more accurate tomography model. After the velocity model was created, I worked on changing the ratio of x and y position components.Then a new tomography model was created for each change in made to the ratio. This process is only in the beggining phases and will take up the remainder of the time I have to work on the SSIP project. As of Friday afternoon, it was officially time for me to start working with Rachel on IDOR.  Friday we had specialized training in order to be able to successfully use Trimble gps units in the field. We will be using the Trimble over the next three weeks in Idaho. In Idaho we will be surveying station sights for the deployment of seismometers in August. Before heading to the airport to leave for Idaho, I got to go on a hike to the Cascades. The Cascades ,pictured below, are an amazing set of waterfalls located near Pembrock, Virginia. The hike was a wonderful four mile hike in the shade of the trees on a hundred degree day. My week was extremely pleasant at work and during my free time. I am excited for the upcoming weeks that will be spent in Idaho. Tune in next week to hear all about field work in Idaho. Goodbye for now. Sincerely, Amanda  

2012-07-12T19:32:53-05:00 http://www.iris.edu/hq/internship/rss/interns/c_write_hello_world_again

Shortly after last week's post, I managed to make a map in GMT which plotted the locations of the seismometers used in collecting Oklahoma data. Compared to all the fancy maps I've seen come out of GMT, I won't lie, mine is pretty plain and looks like I could have made it in Microsoft Paint (and in fact, it likely would have just been easier to make the legend in Paint...) That said, it gets the information across, so I oughtn't get too worried about not producing aesthetically-riveting graphics. Afterwards, I managed to make another map displaying known fault lines in Oklahoma, which looks even less fancy than the first map, because at least the first map had an outline of Oklahoma within its frame. All is vanity, all is vanity. In attempting to make the second map of fault lines, I tried to write a Unix script to parse the text file of faults that my mentor had given me in order to avoid having to manually reformat the text file to GMT's wishes. This ended up being a lost cause, as my attempt to output the contents of one text file into ten separate text files was thwarted by various technical difficulties, not in the least being that I have limited knowledge of shell scripting. A variable was supposed to be recognized as an integer (it was an integer parsed from a string), but was repeatedly thwarting my attempts at evaluating the variable. I thought that variables in shell scripting were context dependent, and therefore there should be no difference between "4" and 4, and everything on Google told me so as well, but it still wasn't working. The attempted shell coding took me a full day. I then gave up and manually parsed the text files, which took me all of fifteen minutes. Moral of this story: figure out what battles are worth fighting. Afterwards, for a change of pace, I began to figure out how to use the focal mechanism calculator HASH (for HArdebeck and SHearer, the creators -- what if they had called it SHHA instead? It'd be like doing a dance move every time you said it. I imagine it with jazz hands). HASH is widely used for calculating the focal mechanisms of local earthquakes; it's a Fortran 77 based program that incorporates margins of error, disparities in velocity models, and lots of averaging to come up with the best fitting focal mechanisms. Finally!, I thought to myself, I can use the data that I've picked! Not so fast! retorted the f77 code. I'm a coding language from the 70s that doesn't even have while-loops, and therefore I'm super picky about everything, especially how you format your text files! You won't get past me that easily! Thus, ascribing to Sun Tzu's saying of "Know your enemy," I've read up on f77. I've learned what asterisks in the read / write commands mean. I've learned its formatting conventions. I've watched as the go-tos directed me down a level, or up a level. I've felt gratitude towards more modern languages that have gotten ridden of numeric labels. And thus, I've begun to figure out what the program is asking of me, and how I'm to format my text files. We are settling into an unsteady truce, f77 and I.  But the truce only exists due to one more component that has recently come into my life. Knowing how I need to format my text files means nothing if I'm left to tediously insert 51 spaces between station name and station latitude because f77 is obnoxiously rigid. I needed to know how to format text files efficiently. Bash had failed me the week before. And thus, casting around for an aid, I turned my sights to what has been termed "the duct tape of the internet": Perl.  I'm kind of in love with Perl. It's so friendly. It was easy to install. It's so widely used that it even came with a lovely IDE for Windows. It was a bit puzzling to learn, and certainly left me staring at a computer for a good day or so (the tutorial claimed that it could teach me Perl in two and a half hours. It was simply not to be). However, having become familiar with shell scripting certainly facilitated my understanding of the language a bit. It's like shell scripting but better. Nicer. More duct-tapey, but serves my needs perfectly. Thus, with Perl, sed, and a plethora of Windows-based programs that allow me to connect to servers easily, I'm ready to take this Fortran program on. Slowly. Many battles lay ahead, including parsing the Antelope dataset so that we associate specific waveforms to certain events, potentially modifying the HASH driver, and formatting first-motion data. But I shall persevere. I shall be steadfast. Onwards! PS: Throughout typing this blog post, I imagined f77 as a villain wearing one of those tiny black masks that barely cover your eyes. And a cape. 

2012-07-12T15:46:15-05:00 http://www.iris.edu/hq/internship/rss/interns/picking_earthquake_arrivals

This week has been good so far; I've picked earthquake arrivals to find locations for two of my now eight families of repeating earthquakes. By the end of the day I hope to be done with the third and fourth. The weather is finally cooling off a bit here (it's gotten down to the mid 80's a couple times), but is supposed to heat up to around the hundreds again over the weekend. :( I realized that a few days ago I didn't specifically address my goals that I set forth at the beggining of the internship, which involved understanding the codes I am using, beginning to understand the limitations of the theory (and what it means to Christchurch), and being able to make good figures for the project. So here it goes... I am understanding how to use the codes and how they work very well for the most part. I will probably have a couple more to understand before it is all said and done, so I will have to revisit this later. I haven't yet had to make any figures with scripting, only GISMO-created plots. I should begin doing this in the next week or two with GMT however. So I will update you all on that. I think of these goals I have made the most progress on understanding the theory better. There have been a few instances where I have seen weaknesses in the theory's slip estimates just due to the methods of finding repeaters. But for me to gain a full understanding of how this affects the end result will require more knowledge about how the final data set turns out (after I get the locations and focal mechanisms). At this halway point, I think I've made pretty solid progress on these three goals and am hopeful that the remaining weeks of my project will wrap them up nicely.   Cheers! Ryan

2012-07-12T11:25:50-05:00 http://www.iris.edu/hq/internship/rss/interns/week_five1

Last week I continued with the preprocessing of my data set in ProMax. Because we shot the line backwards (they like them to run W. to E.) and the line was long enough that we had to use two RXs and two cables of takeouts, it means there are a lot of little things I need to get my head around first, while using ProMax, which makes the process move a bit slowly. Again, at the beginning of the week, I sat down with the main ProMax guy on our team and took notes as he went through his own data set. We also went through the log files I had made the week before to confirm that there were no mistakes. On the files, I have to keep track of which stations are on which cable, how the new FFID numbers match up to the old, and how many takeouts we want to be read by each RX (when we switch over to the other cable, we also switch the placement of the RXs and what they’re recording because one of them is apparently much better than the other). That process was relatively straightforward, but involved a lot of thinking about how the RXs were placed and how the switch, midway down the line would have affected which stations were being recorded. Once the log files looked good, I was able to get onto ProMax and go through all of our shot gathers. For each old FFID (which corresponds to each shot), I had to go through the shot gather and find bad traces (which would correspond to bad takeouts). I had to do this for all 135 shots on the one RX, and then for all the shots around the middle point for the other RX (because it is less sensitive the data is not nearly as good from this instrument). Once I had a sense of bad traces, I began looking at receiver gathers. These look a lot like shot gathers, but instead of showing every trace for each individual shot, it can show you every shot recorded by each individual trace. I then through all the traces I had thought were bad from the shot gathers four times- on each instrument I had to look at the receiver gathers for before and after the switch independently. From these receiver gathers, I could get a sense of the range of shots over which the traces were bad and make note of which traces we were going to ignore for which shots. Once I had made another log file with all of this information, I was able to begin putting the information from the log files onto ProMax. To begin with, I just have to use a fake geometry, which calculates the coordinates of each geophone from the geophone spacing. The first geophone is arbitrarinly taken as (0,0), and then each subsequent geophone moves 5m down the x-axis. Eventually I will get a file with the real coordinates of each shot point (found using GPS), and input this into ProMax. In the meantime, I used a few programs already on the system to create a few basic shot files that take note of how many old FFIDs, stations, and new FFIDs I have. I then input this onto the ProMax server using a series of flows that have to be done independtly for each RX instrument. Once this information has been fully input (right now there’s a few inputting commands I need to find and put into the ProMax system, which should have been set automatically), I will be able to check that there are no strange offsets recorded on any geophone (which could mean the geophone moved during shooting) and I will be able to remove any bad traces and shots, as well as put in blank signals for any skipped shots. And then of course, happy late 4th of July to everyone! I can't say I did anything too exciting besides a barbeque in the backyard with my family, but it was definitely nice to have the day off!

2012-07-10T11:39:27-05:00 http://www.iris.edu/hq/internship/rss/interns/week_5_-_to_sydney

July 2 to July 6 This past week was a successful and short one. I felt really good about my progress because I got the big code to work. The big code is how I think of the code Mallory gave me that creates the dispersion curves. There is still quite a bit to do with the code because I need to tailor it to give useful results for what I’m working on, but it now does exactly what it was written to do with no errors on my computer which was a major accomplishment. So now I’m at a place in my research where I might be able to write a more complete and accurate project description, which is exciting. Stay tuned for that. The final output of the big code for this week was two different dispersion curves, one not using the phase matched filter and one using the phase matched filter. These dispersion curves aren’t particularly helpful right now because they are an average of all the stations response from one event. I’m now going to work on making figures that have all the dispersion curves on them without averaging. I concluded this week by giving a short presentation to the group I work with. The group now includes three PhD students and three other interns, it has grown since I arrived. We had another PhD student, Maria, and another intern, Jerry, arrive this week. Maria is from Croatia and Jerry goes to Princeton, I’m looking forward to getting to know them better. I really like working in this group, everyone is very friendly and helpful. I missed the webinar because it occurred at 4am my time while I was in Sydney, I tried to wake up but it didn’t go so well. I’m looking forward to seeing it though, and catching up on that homework. My brother and I spent Thursday night to Monday night in Sydney and we had a great time. (That’s why this post is late as well.) We went to the aquarium, the wax museum, the wildlife park and the Sydney tower. We walked across the bridge and went to the Opera house and the Royal Botanical Gardens. Here’s the part where I make up for not having enough pictures in my other blogs. Till next time! I hope everyone is having as great a summer (winter) as I am!  

2012-07-10T00:34:35-05:00 http://www.iris.edu/hq/internship/rss/interns/well_thats_no_receiver_function

Today was a somewhat frustrating day.  Simply put, the receiver function code did not seem to create a decent model, as seen in the attached figure.  After changing the water-level parameter as well as add in the Gaussian Filter, I still could not clean up the Signal-to-Noise ratio, that would allow me to see the P-S conversions.  On the bright side, my advisor and I have a working code that we can build off of and stare at for the next couple of days to see what we can do that may help fix our problem.  This deconvolution method is known as the water-level deconvolution method, working in the frequency domain, so tomorrow/rest of this week if we do not figure out what is wrong with our present code, I will investigate new receiver function deconvolution methods, such as working in the time domain or using an iterative deconvolution method.  I have been doing a lot of reading on numerous journal articles, and I am definitely understanding the process of creating receiver functions, but it's just applying that process to a new computer program that is becoming very difficult and frustrating.  I guess this is all part of this IRIS learning experience: finding ways to troubleshoot through problems to hopefully come up with a solution. More updates as this issue is hopefully resolved. Greg (NOT A RECEIVER FUNCTION I WANT)

2012-07-09T17:39:17-05:00 http://www.iris.edu/hq/internship/rss/interns/beginning_figures_of_receiver_functions

Hi everyone,  I'd like to update you all on this past week of progress made regarding receiver function analysis.  Kasper, my advisor, and I have been working with this Python program, Obspy, new to the both of us, but we finally finished the first step and created a figure that contains the vertical, radial, and transversal components of a seismogram (See figure below).  This is a great step forward because now I can use these three components in the next process, known as source equalization.  To put it simply (and to practice writing my research for the layman to understand), three components are needed to isolate the receiver response from other effects that create seismic waveforms.  Now, the next step is to use deconvolution, a somewhat complicated mathematic equation using Fourier Transforms, to create the receiver function seismogram.  Deconvolution takes a signal and removes these effects in the signal, to leave only the pieces of the signal we want.  Now all I need to do is add in some filters (both water level and Gaussian), as also mentioned in Erin's blog!   Next week I hope to get as far as I can on the process for one receiver function, so I can hopefully copy this process for more than seismogram.  The process is going a little slower than I was expecting, but I guess this is what happens when one is working with a new code and new program.  More to come next week!  

2012-07-09T16:56:09-05:00 http://www.iris.edu/hq/internship/rss/interns/recognizing_my_successes

Sorry I've been M.I.A. for a few days; the past week has been a rewarding albiet stressful one. I spent a good portion of the week continuing my cross correlations on a new fault segment. To date, I have discovered about 7 different repeating eathquake families on 4 different segments of the Greendale fault system. During a meeting with my advisor, we decided that since many of these earthquakes don't show up in the GeoNet catalog as events, I will need to find an earthquake location for most of them over the later portion of the internship. This will allow me to further determine which earthquakes are actually repeaters. Unfortunately, I haven't had much time to work with GMT yet to make figures, but once I have the new earthquake locations I'm sure this will be one of the next logical steps. On Friday afternoon, we had an interesting seminar with Tiffany Lohwater, about the troubles of communication with non-science readers or listeners. The two areas that struck home most strongly with me, after a couple of poster presentations in Colorado, were not necessarily knowing the knowledge of your audience, and dealing with an audience of mixed experiences. These are issues that I never conciously thought about, which will hopefully help me out a lot in future presentations. On the personal side, my parents came into town for the 4th of July! The were staying at a hotel only about a block from my house, so travel to and from Capitol square with them was very convenient. We got lots of good food, went to a great botanical gardern, and even got to watch a great fireworks right  alongside the lake. I'll be back to share more later this week!   Cheers, Ryan

2012-07-09T10:05:50-05:00 http://www.iris.edu/hq/internship/rss/interns/week_5_tying_up_one_end_for_now_part_2_emerges

Since my last post was also a bit late, you heard some about my last week as well.  I found better ways to look at some of my errors, and interpret the points that don't seem to match.  I had record sections to look at arival times. Most of what the second part of the week was doing was tying up my control group, which I revised to be a full 5 hours. I've been going through my old picks with my criteria of having an event with distinguishable waveforms on 6 stations.  I've been taking note of when these criteria were not used, and I won't use them in my final analysis.  I've also been filling in some gaps of time, and am nearly finished. I've also been looking more closely for a new time to start picking.  My control period was in the middle of the night, so when there is the least water delivery to the glacier (there was not precipitation or recent precipitation, it was cold so less melting influence from insolation).  Talking with my advisors, we have decided to look at a time period that also did not have precipitation, but was sunny and in the middle of the day, and therefore having more water delivery due to melt.  To make comparisons, I'll be doing picks for the same time duration (5 hours).  I'll be looking for a time within a couple of days of my first set.  I have glanced over some potential days but need to look at some of the photography and various other data to check for the best time. I just went on my first trip to Denali.  It was lots of fun.  Really great weather in the first part of the day, and then it downpoured on us later.  Also, if any of you know the book/movie "Into the Wild"...they moved the bus that Chris McCandless lived in to outside of this brewery about 10 miles away from the Denali Park Entrance.  The original location of the bus, and where Chris lived his final days, was only about 15 miles away.  It was errie in a way and just makes you think. Reflecting a bit now on some of the goals from my first post: I've learned some more linux, but not as well as I'd initially intended.  I've been too busy doing other things not specific to linux (aka, matlab) I can say I'm getting better at having academic conversations, between various social gatherings with grad students, and the conference here. I've gotten some experience in the field (and hopefully will get more).  And now I am confident about being able to do other field work that comes my way. I've gotten in some better shape to some extent, though I'm still not really used to biking everywhere!  I'm more used to walking... And I can say I've been out enough that I've enjoyed exploring some of the area I've been enjoying daylight, but I will be looking forward to nighttime!  And if I'm lucky, I'll get to see the aurora at the end of the summer if it gets dark enough.  Not much progress on next year or post-graduation yet... starting to think a little more about it now. Check out last week's blog.  It's been updated with pictures! Until Next time.

2012-07-09T00:17:48-05:00 http://www.iris.edu/hq/internship/rss/interns/week_4_multitasking

July 3rd, 2012 Last week was filled with multitasking because there was a glacial geology meeting (IGS) right on campus, so I was running back and forth between the geophysical institute and the conference, trying to take advantage of the conference--material, people and experiences--while it was here.  I met lots of cool people from all over the world, and got to go explore out of Fairbanks once during the week.  I got to go to Chena Hot Springs, which included going getting a tour of their geothermal plant, the greenhouse where they grow some of the food they serve, and the Ice Museum, which is actually cooled by energy from the geothermal plant (with energy from the hot spring!).  I'll be sure to include photos soon. I also made some more picks, which can be seen below (just about 5 hours worth of data now).  Definitely good groups and clusters! See below...   Based on Katie's comment from last week, I worked on code to find the events that seemed most out of norm (I picked looking outside of the blue dashed lines) with respect to time residuals.  The red points in the right-most figure are the points that I would look into.  What I've mostly concluded can be found in my second comment from last week's blog.   With help from the supportive community around me, I was also able to make some "record sections," which for those who don't know what they are, essentially plots along your axis relatively.  For example, I was plotting my waveforms with actual time on the x axis and distance on the y axis.  I thought I was a lot closer for a while than I actually was, so it took more time than expected.  Basically, though, if we were to plot a line along the moveout, we would get the velocity at which the wave travels.  What doesn't fall on a line might be due to the composition, or amount of air bubbles, structure, etc of the ice. I also simply worked on some more ways to look at my data, just in case it'll be useful in further research.  Now that I almost have a good control group (goal spanning 6 hours), I'm starting to think more about my criteria for picks.  Before I charge ahead with everything else, I have the following immediate goals: Determine a set criteria for my picks (e.g. at least 6 stations must show this signal clearly enough to pick) Go back through my control group to make sure all of my events meet the set of criteria Find the best way to go through temperature data I'm just now starting to look at.... and... Pick a variety of other times I want to look at in order to determine meteorological influences (i.e. picks times that are cooler and warmer and make further picks over those representative times).  In other words, I'll be going over a more broad scope rather than just very nit-picky small timeframes Also, this past weekend, I went out in the field with a glacial geology student to the alaska range.  Backpacking 10 miles up through 2 passes, though snow, glacial quicksand muck and rivers, to reach the glacier, getting to hike and drill holes on the glacier and moraine, and backpacking back through everything.  It was my first backpacking trip ever, second time on a glacier, first time hiking on a glacier, and my longest hike by the end of it.  It was definitely an amazing experience!  Photos to follow! (Also, that's why this post is late.  Had short notice and needed to pack quickly when I'd been planning on doing this!  Oops!    ) Until next time! (UPDATED: July 9th, 2012) A A. Chena Hot Springs Geothermal operation B B. Ice sculptures at the Ice Museum at Chena Hot Springs C C. The actual hot springs D D. My first backpacking trip, top of our second pass E E. Decent into the valley we stayed in F F. The glacier of our field excursion G G. Drilling into morraine (and glacier, later) H H.  Checking out nearby crevasses

2012-07-09T00:17:14-05:00 http://www.iris.edu/hq/internship/rss/interns/week_three_gearing_up_for_idaho

This week was a slow one for me. The work to get ready for IDOR was minimal. I spent my week studying up on material about the previous work done in the Idaho and Oregon area. We are gearing up to fly to Boise, working out the last bits of info about where our equipment can be bought. We will be surveying in the coming weeks, chosing locations for survey stakes that will guide the volunteers in the future. We will be chosing suitable locations for the seismometers that will be placed in August. I am excited for the field work! 

2012-07-07T22:06:15-05:00 http://www.iris.edu/hq/internship/rss/interns/business_as_usual

This week has mostly been a continuation of cross correlating earthquakes on the second fault segment to try to find repeaters. I'm hoping that by this afternoon I will be able to move on to the next fault segment. Making progress! On Monday I attended an awesome thesis defense, which analyzed the evolution of a Japanese subduction zone using an amazing set of seismic reflection data. After that I had a meeting with Cliff and some of his grad students so that we could all bounce ideas off each other. I was able to show a couple of the graphs that I made the week before in GISMO. This week has been rough watching Colorado Springs be threatened so thoroughly by the crazy wildfires out west. Fortunately, our school hasn't been directly affected by the fire at this point, and it sounds like all of my Colorado friends had the same luck. But I'm off to Chicago this evening to visit a friend!   Beat the heat! Ryan

2012-07-07T16:08:28-05:00 http://www.iris.edu/hq/internship/rss/interns/the_beginning_of_the_end_for_single_receiver_functions

I hope everybody enjoyed a short week due to the fourth of July and was able to see some awesome fireworks!  During this past week I have moved back to IRIS headquarters for awhile as my host at Maryland travels around Europe (not all for fun and games, apparently some seismology is involved as well).  I spent the beginning of the week updating the receiver function codes on the computer at IRIS so that they matched changes I made in the codes at the University of Maryland. Much of the rest of this week has been spent working and starting a number of small projects. A few that I started working on are creating a KML file of the TA stations I will be using and deciphering CCP stacking code I will be using on the TA stations in the future. I felt as I was starting too many new things before I was finishing anything so at the very end of this week I have decided to finish up single receiver functions for the permanent stations. Throughout the process of calculating receiver functions, I have had to make decisions on what the parameters should be and have spent time figuring out which parameters will work best for my data. Some of these parameters include what the signal to noise ratio is, what frequency range is included, what the minimum allowed frequency (or water level) is , what the Gaussian is that is used in the deconvolution, and whether to use the time or frequency domain in the deconvolution. I wanted to wrap up this part of my project by producing some final figures to outline the effects of changing each parameter and write a small paragraph explaining what changing each parameter does. I hope to add this as a small part of my end project. My goal for next week will be finishing all of this up and having some great (hopefully poster ready) figures.  As for the weekend, I plan to attend a free jazz in the garden concert at the sculpture garden just a few blocks from IRIS headquarters and to also just stay out of the heat as much as possible ( its supposed to be 105 F tomorrow ! ) 

2012-07-06T21:33:07-05:00 http://www.iris.edu/hq/internship/rss/interns/holiday_weeks_and_fake_earthquakes

This week has gone past so quickly, mostly because it’s been so fragmented due to the 4th of July. It was pretty nice having a mid-week break, especially one so filled with sun and good food, and it’s like there have been two two-day weeks. It also means that I didn’t get quite as much done this week as I normally would. Some friends of mine from school came out to visit me last weekend, and it was really fun to catch up with them and show them around the area. This story isn’t completely unrelated to seismology, because we visited San Francisco, where we saw a really good exhibit on earthquakes at the Academy of Sciences in Golden Gate Park. There was a simulation house that imitated the Loma Prieta 1989 quake, as well as the San Francisco earthquake in 1906. Never having experienced a real earthquake, I can’t really comment on how accurate the simulation was—they did tell us that there wasn’t any vertical motion—but I’m pretty sure that I felt some Love waves! Later we saw a planetarium show that we’d thought would be about the sun, but it turned out that it was also about earthquakes! Not much information was new to me, but it was entertaining, and they had some very good digital models of fault planes and seismic energy radiating outward. In terms of my research, I’ve been picking events from the four Transportable Array (TA) stations located nearby our own network. It took me a full day to finish the first one (about 180 events); however, I got faster as I went on, and finished the later ones more quickly. Mairi has finally deemed me ready to begin processing our Ruby data in earnest, so I’ve been downloading two years of data for 50 stations. It’s a huge amount of data—the code has been running for almost two full workdays! Currently it’s giving me some trouble, so hopefully I won’t have to restart it completely. When that finishes I’ll finally be able to really dive into the bulk of my analysis. Hope everyone had a good holiday week! For those of you affected by all the crazy weather in the Eastern States, hope that you're coping and doing all right. 

2012-07-06T11:38:29-05:00 http://www.iris.edu/hq/internship/rss/interns/week_five_already

As I mentioned last week, I’ve been working with some new code that makes filtering data much easier. Because the SAC files I requested are so large, it takes around 12 hours to process a year’s worth of data for one station. I’m a pretty impatient person, so this has definitely been a growing experience for me. After more than a week of doing this, I’ve been able to analyze a decent number of stations. Unfortunately, I still haven’t been able to locate any tremor. I’ve included one of the plots for your perusal. The third, fourth, and fifth lines are the most important. They show the filtered bandpasses for (what should be) tremor, earthquakes, and surface waves, respectively. The problem is that the peaks for tremor are at the same time as the earthquakes, showing that it’s likely just energy from the earthquake that’s causing the increase in energy. Dr. Warren suggested that I take a little break from the computer work and write a little about the differences between the SAF and NAF, so I’ll be taking a little break from programming and data analysis for the next few days. By more closely examining the characteristics of each, I’ll have a better idea of why I haven’t been able to locate tremor yet. Thinking about all of this now is also going to help prepare me for writing my AGU abstract, which is a relief. I’m still going to continue to analyze some of the data from stations that are closest to the NAF, though. I guess that’s the good part about having the twelve-hour waiting period! My free-time has primarily consisted of studying for the GRE and researching graduate schools. It’s a daunting process at this point, but I’m also really excited to see all the options I have available! That’s all for now!

2012-07-06T10:51:19-05:00 http://www.iris.edu/hq/internship/rss/interns/routine_week

I’m continuing to spend most of my time locating earthquakes. I’m still able to analyze about a month’s worth of seismic data per week. I think that is a pretty good pace and at this rate I should be able to get through all of the data before the end of my internship. I know that soon I need to start thinking more about an AGU abstract and a journal paper, but I think my top priority is still to get through as much of the seismic data as possible. As I mentioned last week, I’ve been using my time this summer to think a lot about the future. I have decided to explore the possibilities in some of the other programs and universities in the region. I really love Earth Science, and I’m still very interested in geophysical research, but I’ve also started thinking that I might really enjoy sharing my passion in other ways. I’m going to talk with someone about a M.S.Ed. program focused on Outdoor and Environmental Education next week. That’s all I can think of for now. I’m still having a great time in Ithaca.  

2012-07-06T08:54:09-05:00 http://www.iris.edu/hq/internship/rss/interns/the_road_so_far

Hey Everyone! sorry for the late blog, theres just been so much going on lately! ok, so last time I blogged I left off on mapping up earthquake events on lat and lon. I had to map multiple lat and lon plots to reveiw accuracies of associated picks through antelope. After deliberating with Mike, we both came to a conclusion that the parameters that dont pick too many, yet keep a trend in the mapping data would be most suitable to run through 6 years of seismic data. Since then we've been running the parameters which best locates earthquakes and I have been reorganizing the arrivals. As I progress through the internship, some of my goals have been accomplished such as 1) As the weeks move on, I have gotten better at GMT and scripting. I still have a long ways to go to call myself the "Master of GMT" but I'm now comfortable and capable on working with them. 2) The amount of progress throughout the day has been increased as I get familiar with coding and analyzing earthquakes. Similar to David and Greg, I've been analyzing earthquakes through Antelope. Antelope is very familiar to me because I've used it for previous research. The only difficult task that comes with antelope is uncompromising residuals from beautifully picked arrivals. Since the internship has started I've been enjoying my summer at my home university. A bunch of the undergrads in the geology department are still in oxford so the summer has consisted of burrito nights and fun times. I also went to my hometown a couple of weekends ago for a family friends wedding which was a nice break from the lab. I'm really excited to see where my work will take me in the next couple of weeks. Back to work! Noor

2012-07-05T13:23:25-05:00 http://www.iris.edu/hq/internship/rss/interns/week_two5

This past weekend in Blacksburg was a blast. Saturday morning I wandered the local farmer's market and stopped to enjoy a local bluegrass band play. Also, on Saturday there was a summer solstice festival that included clothes and craft vendors, a dog parade, and live music all day. On Monday it was back to data processing.  After calculations to check for reciprocity, the first arrival time picks were redone in order to reduce the error in our reciprocity. The following picture shows the first arrival times picks for shot 30480, which is located in a valley along line three. Figure 1: First Arrival Times for shot 30480. The y-axis is time measured in millisecond and the x-axis is the station identification. The first arrival time picks are shown in red. After the picks were improved and reciprocity was rechecked the data was then used to create a tomography model. This was done using scripts that had previously been made. The parameters of the code were recalculated to fit our specific data. Using the data, input files were made. After running the program the following tomography model was created. Figure 2: Tomography model of the SSIP line three. The y-axis shows depth in kilometers and the x-axis shows distance in kilometers where the zero is set at the western most shot on line three. The next step is to go back and adjust parameters in the scripts and in the initial velocity model. This is done in order to double check that the features in the tomography model are accurate and not the outcome of specific code parameters. Tune in next week for an update on finalizing the tomography model. Goodbye for now. Sincerely, Amanda  

2012-07-03T21:02:15-05:00 http://www.iris.edu/hq/internship/rss/interns/week_two4

Week two has come and gone. I assisted Amanda with little things as she got ready for finishing up the data analysis. We finished up the reciprocity early in the week and made corrections to our first arrival picks as needed. After this stage we converted the files and compiled them for use with Professor Hole's programs. Amanda has been working to get a model of the subsurface layers below the salton trough. I have been spending my time reading articles to become familiar with the geology and historical work done in Idaho for the IDOR project. The IDOR project looks at the evolution of the continental margin where it meets up with accreted terranes. Basically, the North American continent used to end mid-idaho. This was the ocean-side property of a long time ago. Island arcs of volcanos that had formed in the Pacific were slowly brought toward this boundary by the subduction zone and eventually smeared off onto the larger continental mass. These accreted terranes slowly built the west coast as we know it today. Much activity has happened at the boundary between the continental craton and these added blocks, including intrusion my magmas over time. I will continue reading articles throughout the week to get a better understanding.

2012-07-03T11:13:05-05:00 http://www.iris.edu/hq/internship/rss/interns/goals_-_number_four

I always find it a little disconcerting to update this file once a week because everything changes so much in a week. But that’s definitely a good problem to have! • Develop a specific project and write a set of goals for that project. o Use surface wave group velocity dispersion for tomography to investigate the subsurface in Australia o The dispersion allows us to look deeper than just the crust, hopefully get good data for longer wavelengths so we can have resolution at larger depths o Find data from recent (past couple of years) large (greater than M 5.0) earthquakes o Use the data to create dispersion curves o Use the dispersion curves to do tomography o Compare tomography from my results to other maps of Australia  This will be interesting because most tomography in Australia is done using data from earthquakes that occur around Australia but not actually on the continent • UNIX o I have quite a few new codes I’m using to do the frequency-time analysis that develops the dispersion curves. I understand (I think) all of those scripts and what they’re doing, but they call other scripts which I don’t understand. In total I run four scripts which call nine other scripts, two of which are written in FORTRAN, and two CPiS programs. Then I wrote three other scripts I use in conjunction, one to prepare the data, one to clean up and organize all the output files from the main scripts and one to (hypothetically) extract and plot the final dispersion curves. That last one is what I’m working on right now; I just need to fiddle with GMT a bit more. o I’m learning a lot about UNIX and shell scripting, my goals for now are keep working on my codes, improving and writing new ones as is necessary, and keep learning about the codes I’m using – avoid the black box! o Comment! When I started out I was so good about commenting every step! That’s not efficient but if I want to use this script in the future I will probably have forgotten everything about it and so I should spend some time closer to the end of this projecting commenting on scripts I use regularly. I think that if I used it to make a figure for my poster at AGU I should have a script that is well documented and explained to back it up. We’ll see if I have time to meet that goal. • GMT o I made a nice code that follows on the code that prepares the data which reads the headers and extracts all the station names and locations and the event location and puts all that on a map. So far it’s not a smart code in that it doesn’t figure out the region and the scale by itself, but I have plans for that. o I’ve experimented with some code to plot seismograms and now I’m going to put that to use in making dispersion curves. More news (and hopefully images) from this soon. o I’m really excited to finally be making some figure that actually might mean something! Still a long way to go but it looks like I have a project that I can make some good progress on now and I’m feeling very optimistic about this. • CPiS o The scripts that Mallory gave me call several different CPiS programs and use SAC. I’m glad I spent time learning both those programs. For now I don’t have any new specific goals regarding CPiS, other than attempt to understand exactly what they’re doing when I use them in other scripts. • SAC o The code that prepares the data does most of the work in SAC, changing the headers and updating the origin time. I mostly understand what the code Mallory gave me uses SAC to do and my goal for that is fully understand those parts of that code. o I don’t really do any data filtering myself, it’s all integrated into the CPiS programs, so I’d like to learn more about that too. • Understand what group velocity dispersion is used for and be able to communicate knowledgably about it. o I have some papers and a thesis to read about this topic and its uses in tomography so I’m looking forward to being more informed about that. Hopefully soon I’ll have some more specific questions and better ideas for exactly what I’ll be working on and looking for. • Be able to produce a poster which describes my project that is up to professional standards for AGU. o Once I have some figures I can start thinking about writing an abstract. That deadline for AGU is definitely going to sneak up really fast. o I’m making an informal presentation to my group on Thursday about what I have been and will be working on. This will be helpful for defining what I hope to accomplish and getting an outline of what I’m working on. I think this will help with abstract writing and general clarity about my project, for myself and my peers. • Maintain this blog about what I have accomplished and my goals. o Keep posting goals on Tuesdays and general blog on Fridays. Keep including pictures. Start including pictures from my work. • Explore Australia! o My brother and I will be in Sydney from Thursday to Monday so that will be nice. I’m looking forward to having lots of pictures!  

2012-07-03T03:05:05-05:00 http://www.iris.edu/hq/internship/rss/interns/week_four1

  Last week was interrupted by more fieldwork right tin the middle, but I did finally start to get looking at real data. On Wednesday we went back to Point Año Nuevo to do another seismic survey on the San Gregorio Fault. We were slightly further north than last week, and this time we were actually on private land, on the historic Cascade Ranch. The farmers let us do the survey right through their land, partly because they’re actually hoping to use the subsurface images we produce to precisely locate the water table in order to dig more water wells for the farm. We used the same procedure as last week and our line was again approximately 600m, but this time we did the entire data collection process- S and P waves- in one, very long day. On a side note, the day before we went out I had another learning experience when one of the government trucks we were driving to the warehouse died on us right in the middle of an intersection. Between the survey and the warehouse we had to get out 2 or 3 times to push the truck and jumpstart it. Most of Tuesday afternoon was just spent getting this car to the warehouse, loading it up, and waiting for it to be fixed so we could get back to the survey. It has made me realize how much time, in a job like this, one actually spends on logistical issues rather than data analysis! Then finally on Thursday and Friday I could begin the data analysis process. To learn the process, I sat down with the main computer guy on our team and watched as he started processing the data from a line the team did a few months ago over in Berkeley. Then, from the notes I had taken watching him, I began the pre-processing steps to turn the raw data and field notes into actual workable data (a process I’ll be working on for a while). The first step is to backup the raw data from the RX machines we use in the field onto a disk, during which time you also have to turn the many files the machines created in the field (each shot is recorded as its own file) into one larger file. From there, it can be put on the computer and entered into the ProMax system in a SegY format. Once the data is actually on the computer, one still needs to go through all the field notes before even looking at the results on ProMax. In the field our main tech guy takes down each shot and records at which takeout it was and then makes note of when we had to repeat shots, skip geophones, or simply when we had bad shots (the instruments record and save a file for every shot, even the bad ones). My job was then to put the field notes into a log file that, using some preset syntax, notes when the shots are very good, when they’re bad, when we skipped something, when a takeout was offline etc… It seems pretty simple, but you have to be careful that all of the takeouts and geophones recorded are correct. Plus, we do all of this on the Vi editor on the terminal, which I didn't know at all beforehand. It’s not too tricky, but it did take a while trying to input all of this data when I’m still learning the commands for the editor. From there, I used a pre-set code to turn that log file into another one that gives each shot a new FFID (each shot, even the bad and repeated ones, is initially given an FFID number that begins at 1001), by eliminating bad and repeated shots. In my case I also had to reverse the order of the FFIDs since the survey lines conventionally run west to east, but we shot east to west. The program is useful for creating a template for the file, but in reality I had to spend a few hours manually updating it so it counted stations, channels and takeouts correctly and didn’t throw out the wrong shots. Finally from that log file, I created a third file that shows the instrument layout (there are two RXs in the field), the shooting layout (if we had changed shooting type), and the data parameters. Again, it’s pretty straightforward but is pretty tedious and involved a lot of number crunching and checking. There’s a million different ways to make sure you’re on the right station or takeout, but once you do find a mistake, it always takes a while to fix it! Those are all the preprocessing steps I was able to get through at the end of last week and so hopefully tomorrow I’ll be able to learn and implement a few more. There’s about 24 distinct steps to preprocessing and data input that I have to go through before I can even start picking data, but fortunately each day becomes a bit easier as I become more comfortable with the terminology and computer programs. Below I’ve attached two screen shots of what the log files look like.  

2012-07-02T17:32:22-05:00 http://www.iris.edu/hq/internship/rss/interns/mystery_pulses

One of the most frustrating things I've had to accept has been that not all of my data will be useable.  In fact, well over half of my data are most likely not going to yield useful results--either SplitLab produces an error, or the SKS wave signal isn't distinct enough, or the phase has traveled from a null direction (perpendicular or parallel to the fast axis of propagation), or the seismogram is obscured by noise, or...  Basically, there can be any number of reasons that a seismogram is bad.  And as someone who as a matter of principle doesn't like to waste (evidence: earlier this week I accidentally left a jar of marinara sauce out all day and it went bad, but I waited several more days before actually throwing it out because I felt bad about not finishing it) it can be difficult to just skip over a seismogram.  However, I've had to learn to recognize when one isn't going to give me a good measurement right away, because otherwise I'm just going to spend a long time trying various time frames and filters and never going to gain anything meaningful. Example: Alex (another undergrad intern, who is using the same methodry I am but for a different area) and I have both noticed that seismograms sometimes show what I like to call Mystery Pulses--wave packets that occur periodically but at different times on each component, such that they block out any other sort of signal. (also guys, I'm really proud of my arrows and text box on this picture) Whenever I see these pulses, I know that there's no way I'm going to get a useable result.  Sometimes I don't even realize that they're present until I change the filter, zoom out, and recognize, with a small quiver of horror, the unpleasantly familiar oscillations of these infernal Mystery Pulses of Doom.  Not wholly unrelated, anyone else realize that they've become far too emotionally invested in some squiggles on a computer screen?

2012-06-29T13:03:17-05:00 http://www.iris.edu/hq/internship/rss/interns/red_white_and_back_azimuth

Happy forth of July from the nation's capital! The title of this weeks blog is not only for the fourth for overcoming the first problems I had encountered with the matlab code during the second week of the project where the azimuth was being calculated incorrectly. Luckily, since then I have had no major problems figuring out the code and running it for other stations.This week as been challenging as I have run the same calculations many times, but I am glad to finally be done (for now) with calculating the receiver functions for the permanent stations. I am working on writing a KML file for Google earth that will show where all the stations are located and have some basic information about each one that I hope to be able to add to one of my next few blogs! After calculating all of the permanent receiver functions I was happy to to have some time to look through them . I was able to see that the New Madrid seismic zone stations produced receiver functions that were much harder to interpret. To get better results I plan to request data of earthquakes down to 5.6 instead of 6.4 For the other stations I ran an updated phase weighted stacking code to replace H-k stacking. The results on the good stations were about the same, but for some of the less clear stations, the phase weighted stacking made a great improvement and the moho depth and Vp/Vs were much improved. Also, this week I picked out TA stations from around the Mississippi Embayment/Reelfoot rift as well as around the mid continental rift which I will hopefully use later to create a CCP stack of the data. Outside of lab I was able to head to a beach in Maryland this weekend and enjoy some fireworks and friends. I was able to have mussels and crab for the first time and was supervised to find that they were delicious and fun to eat! Although the beach was great I'm ready to turn in my flip flops and towel and get back to working on receiver functions.

2012-06-29T12:29:02-05:00 http://www.iris.edu/hq/internship/rss/interns/half_way_through

This week I have been locating earthquakes! I’m continuing to get through about a month of data per week, and there continues to be a lot of signal left to pick through. The summer is going by really quickly. I have to go back to New Mexico August 15, so I think I am about half way through my time here. This is the first summer, since I’ve been in school, that I haven’t been taking summer classes. It’s been interesting to be doing something that seems much more like a job than school. I think when you’re busy with classes, short term goals and deadlines it is easy to lose perspective of where you are headed in life. Since I’ve been at my internship I have been almost constantly thinking about where I am headed and what I want out of my education. I think that I’ve decided I’ll be taking a long break after I finish my B.S., before making any decisions about graduate school. I haven’t made much progress on my work for the museum, it’s been sort of a weird week for me, but I am looking forward to making some significant progress next week.  

2012-06-29T11:32:35-05:00 http://www.iris.edu/hq/internship/rss/interns/here_comes_the_sun_and_heat

This week I’ve been turning my attention away from triggered tremor and am now on the quest for ambient tremor. On Monday, I received some code that has made data analysis infinitely less complicated from Stefany at Miami University (she’s also a former IRIS intern!). I’ve primarily been downloading data from IRIS for the YL network so that I can analyze it all later. Let me tell you, this is a LOT of data. There are 39 stations in this particular network, and I now have data from when they were first installed (some in 2005, the rest in 2006) to when they were taken down in 2008. Yesterday and today I have been working with the code Stefany gave me, and it takes quite a while to process. For example, the first script processes data for a given station an hour at a time. It takes about 12 hours to go through an entire year just for one station. Once that’s complete, I’m able to filter the seismograms, similar to what I was doing before, at three different frequency levels to differentiate earthquakes, surface waves, and of course tremor. I’ll include figures next week after I’ve had the chance to go through more data. Yesterday was a record-breaking day for St. Louis! Apparently with a high of 108 (!!!) this was the hottest day in the city in almost 60 years. Yikes. On the bright side (literally), today will be a slightly cooler 105. I’ve never been so thankful for air conditioning. That’s all for now! 

2012-06-29T09:20:16-05:00 http://www.iris.edu/hq/internship/rss/interns/week_4_cake_friday

June 25 to June 29 This week I made some good progress. I now have a code that prepares all the data from the seed file so that all the SAC headers are updated and the origin is the earthquake time and all the traces are the same length. Mallory, a PhD student here, gave me a code that extracts the group velocity curves. It mainly uses a frequency-time analysis which has multiple filters to determine the arrival times and group velocities at a variety of periods. The code I was given requires many steps and many other codes and programs to run so I first spent time going through it and getting it to work for some of Mallory’s data on my machine. This took quite a while because all the different file paths and other programs called by the script had to be set up or modified. It was also written in bash and I had been learning about writing in tcsh, which isn’t completely different but there were several new syntax things to learn too. We did manage to get everything working for the original code and data on my computer. Then the next task is to get it working for my data. Fortunately the program I wrote for preparing the SAC files did everything we needed to do to prepare the data except for change the delta so there weren’t quite so many data points. That was an easy fix though and I felt really good that I’d actually created a helpful script that did what we needed it to. So my SAC files are ready for analysis but I need to change some things in her script because she was doing noise analysis and I’m looking at earthquakes. Most of what I’ve had to change so far is file paths and naming conventions but I also need to make sure this is providing a helpful output. That will be what I work on next week. On a totally different topic, one of the traditions here at RSES is teatime. It’s a great way to meet the other students and take a break. The students also have a teatime tradition that every Friday is Cake Friday and someone brings cake for the group. Most of the students here are gone right now, taking a winter holiday or doing fieldwork or at a conference. So it’s a small tea group and it seemed that everyone had taken their turn to make cake recently, so today it was my turn to make the cake! I did not have any baking ingredients but I checked in the house and there was a muffin tin so I decided I would make muffins. It was fun to bake! Another really good thing about this is that it forced me to buy the basic ingredients for baking. Cake Friday is fun. I like the students here and I’m grateful they’re so friendly! On other unrelated topics, my brother arrives tomorrow and I’m really looking forward to seeing him! Also, the campus looks really beautiful when it’s foggy and cold in the mornings.  

2012-06-29T04:24:14-05:00 http://www.iris.edu/hq/internship/rss/interns/the_third_week

Hi! My Third week at Boise State has included both collection of data as well as becoming more familiar with what I plan to do through July.  The seismic data we collected from NHS last Wednesday is finally downloaded and turned into the proper file format for Antelope.  This data set will be extremely important to see if there has been seismicity related to fluid flow/injection in the geothermal system.  I've only briefly looked at this data, but next week I plan on attempting to find events/ characterisitic waveforms that correspond to these injections.  There are a couple of steps that need to be accomplished before identifying these events: 1.  Can I flag and catalog events during the time of data collection, and match these events up with the events in the NEIC database?  If so, these events should be removed from my data set to make the data more manageable in finding local events that were not catalogued in the NEIC database. 2.  Once these larger, regional/global events are removed from Antelope's Datascope, I will need to figure out what exactly I'm attempting to look for!  I will need to answer the question, what kind of characteristic waveforms are generated from fluid injections in a geothermal system?  I am going to search through previous research to see if there is any information on what these waveforms may look like. 3.  Lastly, I will need to figure out which filters are suitable to pick out the clearest waveforms.  Additionally, I have been reading up on receiver functions concepts, Fourier Transforms, deconvolution, etc., to attempt to understand the theory behind how receiver function imaging is generated.  One of my advisors, Kasper, has been spending this week trying to figure out how we can use receiver functions in Python (ObsPy).  Though both Kasper and I have not had much experience with this program, we are playing around with sample data sets to see what this seismic python application can create.  Additionally, we have received code from a receiver function guru that visited during the IRIS workshop, and we hope to try and decipher this code and use it with our data.  The main step in this receiver function project is to use a code that picks teleseismic events from Datascope that are greater than a magnitude of 'X', and events at X-Y degree epicentral distances.  I'll be sure to update everyone on how this code is progressing next week. I plan on relaxing this weekend in Portland, Oregon, visiting grandparents and cousins, and will be right back to work next week on the pieces of this projects! PS Katie, if you have any resources on receiver functions that you think may be useful for a neophyte like I am, I would greatly appreciate it!! Greg

2012-06-28T16:56:40-05:00 http://www.iris.edu/hq/internship/rss/interns/oklahoma_where_the_wind_comes_sweepin_down_the_plain

... and where seismograms and squiggles abound. I've come to appreciate individual seismic stations -- you're lovely, LC01 - LC18. You're not so great, OK009. The accelerometers seem to fail to pick up on a lot of the earthquakes I've seen listed. OKRs are somewhat like teenagers, you never know what you can get -- it'll be perfectly clear for one event and then a mess the next day. I guess that makes sense, as according to my advisors, the OKRs were placed on people's properties -- under a bench, in the backyard, etc. Given that it would simply be impolite to mandate that people (and their neighbors) never use their backyards over the course of a month after they've so generously volunteered their properties, I guess I'll have to live with the inconvenience. I think I've come into the last few days of picking, with a sprint toward the finish -- I've gotten to picking the magnitude 2.5s, so the signals are a fair bit softer now. That said, they also seem a fair bit clearer, so I'm not going to complain.  Last week, we hit a problem with picking: a lot of my seismograms would show waves very softly tapering in, in a fashion that made it impossible for me to determine polarities.  It was an issue of filtering within the seismograms and the difference between causal and acausal filters; from what I understand, when a signal is passed to a seismometer, the seismometer's filter will either look at the data only in the context of the past and present, in which case it's causal, or also try an interpret data in the context of the future as well, in which it's acausal. Evidently, acausal filters are better at capturing amplitudes, which those studying strong motion prize; however, that type of filtering also leads to weird precursors -- the data will show, for instance, that a wave will have began earlier than it actually has. Thus, for some seismograms, I was seeing the precursors and trying to pick from them. In essence, I was saying that an earthquake arrived when it actually didn't; the filtering system caused the signal to rise above the noise too early. Unfortunately, it seemed that some seismometers were causal and some were acausal, so there was no standard procedure on how to deal with the difference. Alas! That said, it seems as if the issue is in the process of being resolved, and my mentors have been busy with converting the data from acausal to causal. Meanwhile, I've been doing more picks! Other than the exciting life of the picking world, I've also wrapped up the nine-part Unix tutorial I was working on; redirection and pipelining are really cool. Script writing also is quite cool, although writing anything more than a basic script requires copious amounts of google to find what methods and commands I'd want to use. I wrote a cute little backup script so I don't have to worry about losing my data any time soon, so long as I'm actually backing up the right data... It's a good thing the internet exists and that there are so many sysadmins posting questions on the userboard, because I pretty much have all of my needs documented somewhere on Google. This is a little less true for the GMT tutorial I've been going through, but I've finally been able to make sense of the syntax, variables, and options. So that's quite a relief; knowing what the options do makes me feel considerably more at ease with typing all the -Rs and -Bs followed by numbers and mysterious slashes. It's amazing how much better one feels about a topic once you sit down and parse through the language for a bit. I think we're moving onto focal mechanisms some time in the next week; this should be good! Over and out, M

2012-06-28T15:06:04-05:00 http://www.iris.edu/hq/internship/rss/interns/week_6_and_lucky_7

Hi Everyone, Sorry for the delay, but everything is ok. These last two weeks have been intense, and if you all don’t know yet I’ve been fasting for these past two weeks. It has been a great experience so far, and I learned quickly that the first thing you can’t do is skip out on a drink or meal. So far I have been analyzing 900 seismograms from approximately receiver stations 300, and I should say that it is a timely process. The four earthquakes that I’m focusing on is the Western Brazil in 2010 (6.2 Mag. occurred at a depth of 581.20m), Peru-Brazil border in 2008 (6.4 Mag. occurred at a depth of 154.0m), Peru-Ecuador border in 2007 (6.8 Mag. occurred at a depth of 122.9m), and another EQ from Western Brazil that occurred in 2002 (6.9 Mag. Occurred at a depth of 534.3). I had the opportunity of utilizing SAC in order to indicate where the P (T5), sp, (T9) S (T7), and SsPmp (T8) arrival times are located. After analyzing all 900 seismograms and picking the arrival times, I assumed that I was finished with the majority of the work, on the contrary, no, I had to then compare the bulk of my seismograms with Mike’s seismograms. I did this task by plotting my time offsets and comparing them to Mike’s time offsets, how did I do this you ask? I honestly didn’t, the program (which is EXTREMELY complex) was already prewritten in order for me to run my time arrivals through the program and create plot with the different magnitudes that occurred across the nation. When I ran the program for the first time I realized that I wasn’t near the finish line yet. In comparison to Mikes plot, his was colorful and revealed some type of trend, mines was a colorful with a bunch of black triangles and no trend (the black triangles = I didn’t pick a SsPmp time arrival for that station in that data set because it wasn’t clearly visible). Therefore I had to go through all of the seismograms and pick/re-pick the SsPmp time arrivals. We also had the chance to review a paper written by Gregory C. Beroza on Slow Earthquakes. In all, and I encourage you all to read this paper, it was conveying that slow-slip events (SSE), episodic tremor and slip (ETS), tremor, low frequency events (LFE), and very low frequencies (VLF) correlate with the occurrence of slow earthquakes. The results gives the reader more of an understanding of how a slow-slip event can only occur if you have tremor, which me personally I don’t believe, but the author goes on to reveal that there is some deviation between the source of the tremor and slow-slip events (i.e. love waves, tidal forcing, weak faults, etc.), and that even though the slow earthquakes occurred in a deep extension of major faults in this study they can possibly occur in more shallow depths in the near future. It also point out that Slow Earthquakes usually occur in younger sediments. But enough about that, if you’re interested in reading it just email me at Saro357@yahoo.com, otherwise, I’m going to continue to tell you all about my 2 weeks. Lately everybody in the office have been busy, but the week was a turn for the better. I had the chance to go to an ice cream social, then right after that I went to a club with Noor and Yi (a lovable Chinese student I met up here) named The Brick. It was a great experience, and I’ve been trying a bunch new things up here, for instance, cooking more than I usually do and…. Oh yea, FASTING. Also, my roommate Harmony adopted a puppy and he’s the best puppy you can have. Here’s a picture of him, and also of some of my work   Well that’s all for this week, Oh! I almost forgot, Mike was successfully able to permit an EarthScope Transportable Array site on the edge of Miami’s campus. They have already constructed an underground “vault” at this site, they just need to install the equipment this tomorrow and I’ll be involved in this epic event. I’m so excited. I hope you all enjoyed my blog, God bless, and let me know if you have any questions. Sincerely, Calvin E. Johnson  

2012-06-28T12:22:14-05:00 http://www.iris.edu/hq/internship/rss/interns/week_3_fieldwork

Sorry this is coming so late, but it's been a pretty busy few days and I've only just gotten around to posting this (though I wrote it a few days ago!). Week 4 has had a bit more fieldwork, so once I have a second I'll be writing about that! So my third week of the internship is through and I’ve already almost done with my fourth week. It’s pretty amazing how fast time is moving and it makes me realize that 11 weeks really isn’t that long! This past week was incredibly productive and I was able to spend most of my time in the field, which was spectacular. On Friday the 15th, a bunch of us went north to do fieldwork for the Master’s thesis of one of the students in the office. We went up to the Filoli Center, which is this beautiful old estate, about 25 miles south of San Francisco that was built in the early 20th century (after the 1906 earthquake of course). The gardens and the house itself, which are open to the public, take up about 16 acres, but the entire estate is over 650 acres. It’s located right off Highway 280, nestled along the foothills, near Crystal Springs Reservoir. Most of the estate, outside of the gardens, as well as most of the land in general situated west of 280 along the foothills is controlled by the SF Public Utilities Commission, and so not open to the public. But we got permission to go onto the back roads of the estate to do a seismic survey right over the San Andreas. The line was only 60m, but we had 1m spacing for the geophones, so it still took us the better part of a day. We also had to do both P and S waves. For P waves, because the line was short, we would just swing a large sledgehammer onto a metal plate, wait 2 seconds, and then move on if Rufus determined that the data propagated well down the entire line. For S waves, we had to use different geophones and a larger, solid metal block. Someone would stand on top of the block and people would have to hit both ends of it. I’ll admit, it was pretty nerve wracking at first to see people swinging a large sledge hammer right towards someone’s ankles, but we had no injuries all week! All in all, it was a long, but productive day. It was also great to get out of my cubicle and spend the day outside in such a beautiful setting. The next week, we got to go out again, this time to do my fieldwork. We were using 5m spacing this time, but the line was 600m, so we still had 120 geophones. Between P and S waves, it took us two whole days to do it. Fortunately we had a lot of people helping out, including Lily and Eva- two other IRIS interns working in the area- so the work went a lot faster than I expected. The process was pretty much the same as on Friday, but this time for P waves, we used Betsy-Seis guns, instead of a hammer. To use the guns, you basically have to dig a hole next to the geophone and then place this gun, which honestly looks more like a pogo stick, into the hole. At the end of the gun is a shotgun shell (all blanks). Then you fill in the hole, release the safety, and hit the top of the ‘pogo stick’ with a hammer. That triggers the gun and it shoots the blank into the ground. In the warehouse on Monday we grabbed the wrong shells, so they were a bit too small to propagate down the entire line, but Rufus was still confident we would get clear data. Because we had to curve the line slightly, I’ll have to analyze the line in 3D, rather than just 2D, which should take a bit longer, but isn’t too much extra work (so I’ve been told). This time we were working on the coast at Point Año Nuevo, just north of Santa Cruz (the park is famous for its elephant seals). Besides the poison oak, it was also a great place to work. The fog never came down on us, so it wasn’t too cold and we could both see the ocean and hear the seals from where we were working. Our main tech guy is going to show both Carla (the master's student whose work we did on Friday) and I how to properly download the data from the disks onto the ProMax program, and then I’ll be able to finally start looking at data! On Thursday, on a side note, I also got to go on a fieldtrip. It started as just the new interns and employees in the office, but by the afternoon, almost everyone under 30 in the whole office was there. We went to Hayward, on the east bay, in the morning to see the Hayward Fault where it runs through the city. And then in the afternoon, after a team barbeque for lunch, we went back to Highway 280, to the Crystal Springs Reservoir, to see the San Andreas. It was a less obvious and involved a bit more hiking on the edge of the hills, but we got to clearly see the dip in the land that is the fault. We also got to see a fence that had been clearly displaced by the 1906 earthquake. It’s one of the last sites where you can clearly see displacement (that hasn’t been recreated) from 1906.  It was definitely nice to spend so much time outside this past week, but hopefully, now that I'm getting a better feel for the actual computer analysis process (through looking at a lot of Rufus' old data and papers), I'll actually start to look at my own data soon!

2012-06-28T12:19:15-05:00 http://www.iris.edu/hq/internship/rss/interns/poison_oak_or_mosquito_bites

I had a really great time out in the field for two days with Leah and about 20 other people from USGS this week; Eva was there too for one of the days! We were working on a seismic survey down south along the coast in Ano Nuevo Park. We were working on a 600 meter array along a service road with a beautiful view of the ocean off in the distance! Leah was the PI on the project, so it was pretty neat to see all these people (many of them adults!) working to get data for her to analyze! I worked on putting in and taking out geophones, using a hand auger for the p-wave shot source and avoiding the poison oak plants that were EVERYWHERE (I currently have some itching on my elbow, but I’m pretty sure it’s a couple of mosquito bites…fingers crossed.) As exhausted as I was from two very long and active days, it was nice to get out of the office and see a beautiful coastal area and cool geophysics field techniques! Thanks Leah! Back to work at my cubicle wasn’t too bad, however. I am still working on figuring out what earthquakes make sense to look at in our data. I have a pretty nice looking graph that gets more and more colorful as I add earthquake events to it! In response to Katie’s question on my previous post, I will most likely start by working off previous work in the sense that I will look at how other people have analyzed their data and begin by doing that to some of our data. It’s looking like we really haven’t had any earthquakes recently enough that would be large enough to show us anomalies over the noise of the area on our stations. I will most likely not see any anomalies associated with earthquakes, but even that will be good to report so we can begin to establish the size and proximity of earthquake needed to see any possible anomalies. Here is what my graph is looking like: I talked with Simon about a good range of earthquakes to examine based on the graph. I first have to catalog a little more so that I can make sure we have good data from our stations on the dates of the earthquakes I would be looking at. Then my plan is to find lightning data and look at the data closely in order to characterize lightning events. This will help me not only become more familiar with the data but also help us rule out anomalies we might see that are actually just lightning strikes. Next I’ll probably look at solar storms and other exogenic geomagnetic events.

2012-06-26T13:53:31-05:00