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

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

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

Getting SAC Fill out the online request form. You will receive an which will contain sac as an attachment in the form of a binary compressed tar file. The gives instructions for how to expand and 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 Nov 8-17, 2009Metadata Workshop, Cairo Egypt

Before Running SAC Set up SACAUX and your PATH. Set up SACAUX and your PATH. If you are running bash, then in your.bash_profile file, put the following: If you are running bash, then in your.bash_profile file, put the following: You should now be able to run SAC. Nov 8-17, 2009Metadata Workshop, Cairo Egypt

Starting SAC To run, type “sac”. If it is working properly, you will get something like this: To run, type “sac”. If it is working properly, you will get something like this: sac SEISMIC ANALYSIS CODE [08/25/2009 (Version 101.3b)] Copyright 1995 Regents of the University of California SAC> Nov 8-17, 2009Metadata Workshop, Cairo Egypt

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. 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. sac SEISMIC ANALYSIS CODE [08/25/2009 (Version 101.3b)] Copyright 1995 Regents of the University of California SAC> Nov 8-17, 2009Metadata Workshop, Cairo Egypt

Simple Example Start SAC and at the SAC prompt, type: Start SAC and at the SAC prompt, type: sac SEISMIC ANALYSIS CODE [08/25/2009 (Version 101.3b)] Copyright 1995 Regents of the University of California SAC> begindevices x (for x-windows) SAC> funcgen sine SAC> plot You should get this plot: Nov 8-17, 2009Metadata Workshop, Cairo Egypt

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

SAC> read s.bhe s.bhn s.bhz SAC> qdp off SAC> color on incr list red blue green SAC> plot1 Example: Read Your Own Data Nov 8-17, 2009Metadata Workshop, Cairo Egypt

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