Today I've accomplished a fairly large achievement of the past couple weeks of work. I've successfully summed the residual maps for all OIINK stations for the 2013 data that I analyzed entirely by myself. To add a cherry on top, all the processes and code to sum the residuals across all the stations was done this week while my mentor was out of town! It feels good to have struggled through something and come to the answers by yourself.
To explain a little bit more about what I've done, I'll take you back to my first blog post when I showed you the color map. The map I talked about in that post represented one specific earthquake event. The map I've just finished creating and will show below comprises roughly 100 events. Looking back at what I've done, the task doesn't necessarily seem particularly difficult, yet I learned much more in taking the slow route by myself. Here's the gist of what I had to do:
1. Separate the individual events into azimuth ranges. (I don't really know why I had to do this yet because my mentor hasn't been here, but the 2012 data was separated this way so I just followed the same process)
2. Isolate the files containing the lat, long, and residual data that GMT uses for mapping.
3. Combine these files into a single file.
4. Search through these files for matching stations.
5. Sum the residuals for each station. (Not trivial with ~80 stations)
6. Calculate the averages for each station. (Also not trivial considering each station had a different number of events as a result of my initial editing of the waveforms)
7. Record these averages along with the lat and long values in a new file.
8. Create a GMT code that would map the averages.
9. Run all the procedures for each azimuth range.
10. Repeat the entire process to combine every data point.
Now, some of this was trivial, and some of it was quite difficult for me. I had to look up and learn multiple new Unix commands, as the easiest way to do this was in a shell script. I had significantly adjust the GMT code, as our existing code pulled data directly from our database and I needed it to pull the data from the new files I was creating. There were also some complications stemming from how I had initially organized the files. I definitely learned that the way you think you want the files organized is not always the way you want them organized for the final product. My finished code isn't long or particularly complex, but to see it work just as I intended is satisfying. It's also nice to see the visual results of all the data I've been processing since the start of my internship.
And alas, here is the picture:
The figure clearly shows that P waves arrive quicker than normal in the southwest region of the figure (Missouri). Adjusting the scale to be a bit more color sensitive might show even more trends, although you have to be careful with how you set color scales. They can become quite deceptive if you aren't careful. When my mentor comes back later this week, he'll hopefully have some adjustments to make to improve the figure. Who knows, I may have done everything wrong! Regardless, it's fun to see the averages across all the events and all the stations. Some stations aren't visible on single events because of noise or poor signals, and the averages allow you to see the larger picture with every station. That's all for now, I'll update when my mentor returns to see how my figures have changed. Hopefully I've done at least part of the work correctly!
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