Nothing goes to plan

July 5th, 2010

So it's been a very long week. Mairi and I stayed behind in Elko to finish 24 service runs.  We definitely ran into some major problems: the first day by ourselves we got stuck in a huge mud slick (I maayy have been driving).  After a good 45 minutes of shoving rocks under the tires, shoveling out the mud, and some just general tire spinning, we got a guy to pull us out.  In the process we got a flat tire.  We only got 2 stations done that day.  The next day was more successful: we got 9 stations done but ended the day with two flat tires in the middle of nowhere. We drove on one flat to a tiny town, found 3 old guys drinking beer outside of their trailer home and paid them 15 dollars plus tip to fix our tire.  In the end we finished all the stations and made the drive back to Stanford. 

Wednesday started my actual work on my project.  Simon gave me three different things to focus on: 1. Acquiring the data from a permanent station in Elko as well as from 4 transportable array stations to begin splitting measurements on.  2. Figure out how to use the Splitlab program to perform the splitting and ultimately assess the anisotropy in the region and 3. to attempt to open the RAMP data given to us by Glen Biasi at UNR that was acquired following the Wells earthquake.  I started on the first two goals and ran into major issues with both.  I gathered the station data using a SOD file which bbasically allows you to specify the criteria of the data you want such as the network name, station name, the distance of the event (in our case, 85-110deg is optimal for the splitting), the time frame of the event, magnitude, etc.  Problems occured however when looking at the .sac files because the requested phases are not always picked (P & SKS) and the signal is often so noisy that it is difficult if not impossible to detect any earthquake arrival at all.  Filtering proved to be little help.  I have received a lot of help with this but as of now am completely stalled.

The second project, to begin to work in Splitlab, has also reached a dead end.  Splitlab is a program that allows you to analyze seismic waves for splitting due to anisotropy.  The main principle is that when a wave travels through an anisotropic medium, that is: one in which the crystals have a preferred orientation, the wave splits into two orthogonal parts: a fast direction and a slow direction.  The fast component will arrive first and the delay time between the fast and the slow reflects the thickness of the anisotropic layer.  This program searches through all the possible values of phi (the azimuthal orientation of the fast component) and dt so that the splitting is completely removed when it is back-calculated.  The program displays the components corrected for anisotropy (they should coinside) the energy of the radial and transverse waves (transverse wave energy should be minimized when phi and dt are correct) and particle motion plot (should be linear after correction).  I ran through the practice project with little problem but encountered major problems when I tried to load some of the .sac files I had downloaded from IRIS the problem being that they could not be read in.  This program seems to be kind of shotty and it may be necessary to find a different one.  As of today I am very frustrated at these dead ends...I need data for my project! BUT it's the weekend so I guess it'll have to wait until Monday.  Happy 4th of July everyone!!