Tremor Triggers and Seismograms

June 14th, 2012

This week has primarily consisted of article reading and a little data analysis. I’ve been doing quite a bit of reading about the SAF because it has been so heavily studied. I now have a better understanding of what tremor is and different ways to locate it, and I’ll be applying much of what has been done in studies on the SAF to the NAF.

Here’s a little of what I’ve learned about tremor this past week:

Relatively new idea for tremor to occur on transform plate boundaries; traditionally believed to primarily occur at subduction zones
Fluid movement is one of the proposed mechanisms that trigger tremor
Has been triggered by teleseismic waves from major earthquakes from different parts of the world
- One article showed evidence that the M 8.8 earthquake in Chile in 2010 triggered tremor in California along the SAF

With that in mind, I located 57 earthquakes that have occurred in or near Turkey since June 2005. IRIS had a temporary network set up for about 3 years, and I have been downloading data from specific events. I have looked at data from 9 different earthquakes thus far. Once I have the data, I use SAC (a program within UNIX) to filter the seismograms. I have been filtering the data from 2-8 Hz (these values are based on what I have seen in the literature). I’ve included two figures to help visualize everything. There was an earthquake in western Turkey on October 18. The first figure is the unfiltered, transverse data collected by five different stations, and the second consists of the same stations with the 2-8 Hz filter. My advisor is out of town until next week, so I’ll hopefully be able to provide some further insight next week!

I have been pleasantly surprised by how much easier the programming has gotten for me by this point. I feel much more comfortable with navigating my way through SAC and am able to figure out minor problems on my own. I’m definitely not even close to being an expert, but this has definitely been a huge relief for me. That's all for now!

Figure 1. Unfiltered seismogram

Figure 2. Filtered seismogram 2-8 Hz

Comments

By Michael on June 14th, 2012

Sounds like this has been a very productive week! I am glad that you are feeling more confident both with your content was well as your ability to use SAC. You didn't mention this, have there already been demonstrated examples of tremor on NAF?

By Anna Pfohl on June 18th, 2012

Tremor hasn't been observed on the NAF before, which makes what I'll (hopefully) find a little more interesting!

You must be logged into the CMS to post a comment.