SeisComP Tricks: The Poor Man’s Focal Mechanism

SeisComPers:

Since installing TOAST on our new Tsunami modelling server and the SeisComp Moment Tensor module (scmt), I have been experimenting a lot with focal mechanisms. If you have not upgraded your SeisComP to the professional version, the free version still allows you to play around. Here I show you how to get a focal mechanism to appear on your SeisComp EventS Viewer (scesv) in 3 easy steps:

1. Obtain the focal mechanism of interest from GEOFON (Click on the “MT” links), the USGS, or any other source.

Here we use last year’s 7.6 Mw event in Costa Rica as an example:
http://geofon.gfz-potsdam.de/data/alerts/2012/gfz2012rmfw/mt.txt

2. Next open SeisComp’s Origin Locator View (scolv):

seiscomp focal mechanism 1 300x160 SeisComP Tricks: The Poor Mans Focal Mechanism

scolv (SeisComP Seattle 2013.245)


and click the Location tab and then the First Motion tab. You can now either grab the beach ball with the mouse and roll it around until it looks similar what the pros published OR click next to NP1 (Nodal Plane 1) and NP2 to add the values yourself:

seiscomp3 focal mechanism 2 300x201 SeisComP Tricks: The Poor Mans Focal Mechanism

Manually enter the Moment Tensor with scolv’s First Motion feature


3. Hit the “C” button and the beach ball will automatically appear across the SeisComP system and in TOAST.

seiscomp3 focal mechanism 3 300x201 SeisComP Tricks: The Poor Mans Focal Mechanism

scesv (SeisComP Seattle 2013.245)


Have fun focal mech-ing,

– Branden

P.S. If you are not using SeisComP yet, download it free from GFZ and set up a world-wide earthquake location system from the comfort of your home or office.

3 comment(s) on “SeisComP Tricks: The Poor Man’s Focal Mechanism

  1. Hi Branden,why didnt’t you first pick polarities in scmv picker and then didnt’t fit beach boll to observed polarities? You can estimate FM already with scmv from polarities without any other sources.Regards,Alex  

  2. * scolv (instead scmv), sorry 

    • Alex:

      Great to hear from you mate.

      Absolutely! That is slightly more advanced than I was shooting for but a good point none-the-less. Instead of waiting for the USGS/ GFZ to issue the moment tensor, you can open scolv’s picker and assign polarities to each waveform. These polarities will then appear on the First Motion plot. One can then fit the beach ball to the observed polarities as you suggest. I suppose your method is the real “poor man’s” method and mine is the “lazy poor man’s” method :D

      Please send photos of Siberia ;)

      Best regards,

      Branden

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

Current day month ye@r *