1. 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
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

2. 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.
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

3. 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.
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

4. 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
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

5. Before Running SAC # SAC environment export SACAUX=/opt/seismo/sac/aux
Set up SACAUX and your PATH.
If you are running bash, then in your .bash_profile file, 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.
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

6. Starting SAC user@hostname:/opt/seismo/sac$ sac
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>
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

7. Using SAC user@hostname:/opt/seismo/sac$ 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.
sac
SEISMIC ANALYSIS CODE [08/25/2009 (Version 101.3b)]
Copyright 1995 Regents of the University of California
SAC>
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

8. Simple Example You should get this plot:
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:
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

9. Another Simple Example
SAC> funcgen seismogram
SAC> plot
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

10. 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> plot1
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010

11. Learn More http://www.iris.edu/manuals/sac/manual.html
Data Management Workshop Foz do Iguassu- Brazil
August 13-19, 2010