Week Two

June 28th, 2010

This week I worked mainly on running the data through a matlab script written by Ken Creager that bandpass filters from 2-8 Hz (prime tremor range) and creates envelopes of data, which was then supposed to be written out as AH files.  Well...this didn't go quite as planned.  Elizabeth was gone Monday-Wednesday, and the grad student I'm supposed to go to for help hasn't been around because she was going home.  Thus my main means of help was through email.  Errors kept popping up, and it took a while for us to figure out what was wrong through email correspondence.  It ended up being something with an updated version of matlab no longer being able to write out the AH files using the script we were(I think), so we had to change the output files to SAC files, which solved the problem nicely.  While we were working through the errors, Elizabeth had me work through a GMT tutorial, and then modify an existing GMT map to display my stations and the catalogued earthquakes.  I ended up with a lovely looking map, which I'm still working out a few kinks on.  I tried to upload it just now, but couldn't figure out how to.  Oh well.  

I then began working through the data after it had been run through the script.  I looked at only one component, searching for areas in time in which there was a similarity among the stations.  This is somewhat time consuming, as I had to step through each day in 4000 second increments.  I recorded any times that there was a similarity and then looked back at the original data during those times to see if I could identify tremor.  This was a slightly frustrating process because the tremor was hard to pick out, but I did find some examples of it that Elizabeth agreed were interesting.  The next step is to cross correlate during the tremor intervals in a method that involves taking a six second segment and cross correlating that with the rest of the interval we're looking at, setting a lag of 0.5 seconds between each six second segment.  For now we're focused on just an interval when tremor is occurring, but we will eventually expand this to cross correlate for the entire day.  Elizabeth is going to be gone again starting on Tuesday until the following week Wednesday, so hopefully I can get it working in that time.  Otherwise she gave me some other things to work on, which includes writing up methods of what I have done so far for our poster.  I'm sure I'll be able to keep plenty busy.