SAC An Overview SAC Seismic Analysis Code was

SAC: An Overview SAC ( “Seismic Analysis Code” ) was originally developed by LLNL An interactive program for time-series data with emphasis placed on analysis tools used to study seismic events, e. g. : Fourier transforms Filtering Signal stacking Decimation and interpolation Correlation and deconvolution Seismic phase picking Large program Very simple to get started – I’ll show you how Learn additional and more complex commands later, as you need them Lots of documentation Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

SAC Data Format SAC binary is the standard. A binary SAC file contains an ascii header that describe the binary data that follows. SAC ascii will work. Each data file must contain just one component (no multiplexed data). Data must be evenly spaced time series data. Big-endian byte order – so if you use LINUX (Intel processors) you must convert from little-endian to big-endian. Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

SAC Availability at IRIS The IRIS DMC distributes SAC software for scientists conducting research using IRIS data. Request here: http: //www. iris. edu/software/sac/ Also available: Tutorial, user’s manual, mailing lists for help and development issues, and SAC DHI. Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Getting SAC Fill out the online request form. You will receive an email which will contain sac as an attachment in the form of a binary compressed tar file. The email gives instructions for how to expand untar the file. Untarring the file creates a subdirectory “sac”, which contains a README file, the executable, and all required auxiliary and other files. The executable sac is located in. /sac/bin You will need to add the full path name of this. /sac/bin subdirectory to your $PATH Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Before Running SAC Set up SACAUX and your PATH. If you are running bash, then in your. bash_profile, put the following: # SAC environment export SACAUX=/opt/seismo/sac/aux export PATH=/full_path_to/sac/bin • You should now be able to run SAC. Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Starting SAC • To run, type “sac”. If it is working properly, you will get something like this: user@hostname: /opt/seismo/sac$ sac SEISMIC ANALYSIS CODE [08/25/2009 (Version 101. 3 b)] Copyright 1995 Regents of the University of California SAC> Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Using SAC You can begin to use SAC without data of your own, because SAC can generate functions (impulse, triangle, sine, quadratic, etc). SAC even comes with some sample seismograms. user@hostname: /opt/seismo/sac$ sac SEISMIC ANALYSIS CODE [08/25/2009 (Version 101. 3 b)] Copyright 1995 Regents of the University of California SAC> Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Simple Example Start SAC and at the SAC prompt, type: user@hostname: /opt/seismo/sac$ sac SEISMIC ANALYSIS CODE [08/25/2009 (Version 101. 3 b)] Copyright 1995 Regents of the University of California SAC> begindevices x SAC> funcgen sine SAC> plot • (for x-windows) You should get this plot: Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Another Simple Example SAC> funcgen seismogram SAC> plot Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Example: Read Your Own Data SAC> read s. bhe s. bhn s. bhz SAC> qdp off SAC> color on incr list red blue green SAC> plot 1 Metadata Workshop, Cairo Egypt Nov 8 -17, 2009

Learn More http: //www. iris. edu/manuals/sac/manual. html Metadata Workshop, Cairo Egypt Nov 8 -17, 2009