In order to gain a better understanding of plate tectonics, this study focuses on subduction zone processes. Subduction zones are regions where dense oceanic plates are subducted beneath overlying, buoyant continental plates. As the pressures and temperatures increase along the plate interface of the subduction zone, there is a transition from frictional behavior, observed in the shallower, more brittle regions, to stable sliding. This transition zone, accompanied by dehydration of the oceanic slab, produces episodic slow slip events and low-level seismic vibrations called tectonic tremor. The temporal spacing of these processes in relation to the megathrust earthquakes that occur directly updip of this transition zone, calls into consideration whether there is a direct correlation among these phenomena. If a correlation can be deciphered, the episodic tremor and slow slip may be used as an early warning system to predict future big earthquakes. Based on previous studies confirming tremor is occurring in southern Mexico around the Oaxaca segment, further analysis is being made in this region to learn more about this tectonic tremor and its spatial and temporal relationship to slow slip and earthquakes. The study utilizes three-component broadband seismometer recordings from June 2006 through September 2007 in the Oaxaca region.
As the weeks go by, things are wrapping up. I’ve done a couple hundred source locations that have amounted into a fairly decent map. Eventually, I will go back through and take a look at the outliers to see whether or not corrections need to be made on the pick times. Also, I recently learned how to save sac files and as ps documents. I spent a day going through my data finding prominent non-volcanic tremor events and saving the envelopes of ‘good’ tremor signals. I’ve also been saving spectrograms along the way of tremor and earthquakes such that I can eventually show the contrast in frequencies and intensities between the two seismicities. I’ve been compiling all these now so I have some useful and well-placed visuals for my poster I will eventually be putting together for AGU.
On a lighter note, I made it to the Ohio State Fair this past weekend and got my healthy dose of all things deep-fried. Other than that, it has been pretty low key and quite in and around Oxford.
Such is life, most things never go according to plan. This summer, I have come to realize that research is no exception to the rule! The original plan was to do some cross correlations and waveform alignments to refine tectonic tremor locations in Oaxaca, Mexico. However, we are still waiting for some of the codes from another univeristy. Rest assured, there is no shortage of research to be had in the meantime! Instead, for the past couple of weeks, I have been locating tremor in southern Mexico, a little north of Guerrero. (Say that five times fast!) The tectonic tremor here is amazing! It's so clear, I can sometimes see the p-waves, which isn't always the case for tremor. In addition, I have a program in which to examine the spectrograms of the tremor's energy bursts, just to make extra sure they are not earthquakes. So bit by bit, I am going through the months between 2006-2007 and locating the temporal and spatial distribution of tectonic tremor. I've made hundreds of locations so far, translating into a pretty good looking map, to which I am quite pleased. In the grand scheme of things, the locations are all occuring downdip of the the megathrust earthquake zone in the region, which is to be expected. I will be very interested to see what the map will look like eventually when we get the data to plot where the slow slip events are occuring in addition to the earthquake catalogue. But the verdict is still out on that one until some more tremor can be plotted. Then the interpretations can begin!
Right now though, I am redoing one of the hours using an additional handful of stations to better refine some picks I made earlier last week. It's quite tedious at the moment because my locations are actually getting worse than they were before! So I decided to put it off for a little bit longer and update my blog instead.
However, its not all work here in the Buckeye State. Whoever said Ohio wasn't beach front property should check out my new shell collection! Well, maybe I'm a few hundred thousand years behind the times. . . But nevertheless, a small group of us from the seismology lab and the geology department went fossil hunting on Saturday out in Indiana. There was a nice outcrop near a reservoir exposing the Liberty and Wanesville formations of the Upper Ordovician. There was no shortage of bracheopods and crinoids, but the Holy Grail of the trip was trilobites. Unfortunately, this trip prooved largly unsuccessful except for a few bits and pieces. Must have been out of season for trilobite hunting. It was still a blast and occasionally we got some music to jam to from nearby boaters.
I've been way behind in my blogs, so now its time for some past updates! A week after the IRIS orientation in New Mexico, my research adviser took us (Martin and I) to Utah for the IRIS Workshop. I was home for just enough days to unpack, do my laundry, then pack again! They held the conference at the Snowbird Ski Resort about a half hour out of Salt Lake City. There was still plenty of snow on the ground and some of the slopes were open still. One day it even snowed for a bit!
The workshop was almost like the orientation all over again, except less computer tutorials. It was breakfast, lectures, posters, lunch, special interest groups (town hall-like meetings) and sometimes more talks and dinner. I definitely felt like I was able to commprehend more than I would have just a few weeks ago. Nick was there too, so we usually stuck together to keep ourselves awake during the lectures. Also, just in the spirit of Mike, they fed us snacks between most meals! (except no squirt or twizzlers. . .)
On of the coolest things we did while we were there (besides play in the pool) was take a tram up the mountain. We had a great view until a giant cloud came in and covered everything up. Then it started storming. I also got to present some of my research that I had done earlier this year on Non-volcanic Tremor in one of the poster sessions. But after another long week of lectures and learning, it was nice to fly back and stay put for awhile.
Today is the last day of orientation. I managed not to get burnt this week. Also, despite feeling like I didn't understand 95% of what the lectures were about, I feel like I actually learned a lot, except how to predict earthquakes. The jury's still out on that one. I'm going tom iss all the awesome people I met this week. I'm especially going to miss being fed five to six times a day =( We are going to the San Lorenzo Canyon tonight for a bonfire, a great way to wrap up orientation week. I need to pack up sometime tonight and leaving for the airport around five in the morning.
First blog of the summer. Currently in Socorro, New Mexico! Just went on a morning hike to see some faulting. Learning about unix and matlab this afternoon. Then dinnertime! (probably best part of the day =) And hopefully some ultimate frisbee or wuffle ball tonight.