1. An Introduction to Earthquake Analysis Tools (Part 1) Bill Langin 10/2/02

2. Outline 1.Useful websites 2.Obtaining Data  IRIS-PASSCAL 3.Analysis Programs  SAC  HypoInverse  FOCMEC

3. Some Useful Websites 1.The IRIS-PASSCAL Homepage  The source for earthquake data and software  http://www.iris.edu http://www.iris.edu  Ordering data, obtain analysis software, get station and/or array information, instrumentation parameters, etc. 2.OFEUS Geophysical Tools Homepage  http://orfeus.knmi.nl/other.services/software.links.shtml http://orfeus.knmi.nl/other.services/software.links.shtml  Tools for just about any job… 3.USGS software  http://quake.wr.usgs.gov/research/software/index.html 4.Harvard Seismology – http://www.seismology.harvard.edu/

4. Many tools available on IRIS website - http://www.iris.washington.edu/ Some useful tools: - BUD – online buffer of real-time data - Wilber - Spyder useful for looking at data - Farm - Weed, Xretrieve – UNIX based tools - Breqfast – e-mail based data request method Obtaining Earthquake Data

5. IRIS Data Request Demo

6. The PASSCAL software - The most important software for earthquake data analyses - http://www.iris.washington.edu/DOCS/software.htmhttp://www.iris.washington.edu/DOCS/software.htm - extraction and manipulation of data - format conversion, simple processing, archiving - freely downloadable - UNIX, Linux However, you will also need additional tools and will end up writing a lot of your own code to meet your specific needs.

7. SAC – Seismic Analysis Code - SAC has been around for ~20 years and has been the “standard” in earthquake analysis tools - http://www.llnl.gov/sac/http://www.llnl.gov/sac/ - Freely available for UNIX, Linux - Can be used for just about any manipulation and analysis of seismic data - Somewhat “user unfriendly” - SAC manual is pretty good, online help is better

8. SAC Demo - reading files (SAC, SEG-Y, ascii) - filtering data - picking - etc.

9. Earthquake Location Lots of choices for location programs: - HypoInverse – standard used by USGS for 20+ years - HypoEllipse – created to deal with location in regions with large amount of relief - LocSAT – used by CTBT community - HypoDD – uses “double-difference” technique - SIMUL12ps – simultaneous inversion for location, Vp, Vs And there are many more…

10. HypoInverse - ftp://swave.wr.usgs.gov/pub/outgoing/klein/hyp2000/ - UNIX or Linux - relatively simple to get “up and running” - manual is very detailed and pretty good overall - input files are ascii text, so can be used on data from any source

11. Required Inputs for HypoInverse You really only need 3 files to get started… - velocity model - station location file - P (and S) pick file - there are a lot more “bells and whistles” that you can play with to find the optimal location procedure for your data

12. HypoInverse Demo

13. FOCMEC – A tool for computing earthquake focal mechanisms - http://www.geol.vt.edu/outreach/vtso/focmec/http://www.geol.vt.edu/outreach/vtso/focmec/ - based on first motion polarities - can also include SV and SH polarity and amplitude information - grid search to find all possible solutions with specified number of tolerable errors

14. Using FOCMEC - like HypoInverse, you only need a few files to get started - station location file - file with station name and polarity - file with earthquake location and list of stations to be used

15. FOCMEC Demo