Overview

SAC (Seismic Analysis Code), previously SAC2000, is a general-purpose interactive program designed for the study of sequential signals, especially time-series data. Emphasis has been placed on analysis tools used by research seismologists in the detailed study of seismic events. Analysis capabilities include general arithmetic operations, Fourier transforms, three spectral estimation techniques, IIR and FIR filtering, signal stacking, decimation, interpolation, correlation, and seismic phase picking. SAC also contains an extensive graphics capability. Versions are available for a wide variety of computer systems. SAC was developed at Lawrence Livermore National Laboratory and is copyrighted by the University of California. It is currently begin developed and maintained by a small group of developers working in cooperation with IRIS http://www.iris.edu

This Manual

This manual contains general information for the new user about what SAC can do, how it works, and how to get started. It also contains detailed information for the more experienced user on topics such as how to use SAC macros, how to read and write SAC data files from C or FORTRAN programs, and how the SAC program is structured.

Update Policy

This manual will be periodically updated to include new descriptions and to revise old ones. Please report any errors in this manual to:

sac-help@iris.washington.edu - SAC Help Mailing List

This will help keep it as accurate and current as possible.

Notation

This section describes the notation used in this manual. All of the SAC manuals use a similiar notation.

Uppercase/red words (e.g. READ) identify commands or keywords. They must be entered as shown, although they may be either uppercase or lowercase.

When showing examples of interaction between the user and SAC, a uppercase typewriter style font is used within these examples, with comments about what is happening appearing in lowercase and enclose in parentheses.

Repeating an important point made above, you may enter keywords and options in either uppercase or lowercase. SAC converts these to uppercase before interpreting them. The exceptions to this rule are text appearing within single or double quotes and the names of directories and files. The case of these items is not changed. They are interpreted literally.

Other Manuals

Other SAC manuals include:

A Tutorial Guide For New Users which explains the basic SAC commands with examples for you to try as you read.

Command_Reference Manual which contains detailed descriptions of each SAC command including purpose, syntax, default values, and examples. This manual also contains lists of SAC commands sorted alphabetically and functionally.

Spectral_Estimation_Subprocess Manual which describes a subprocess for the study of stationary random processes. A subprocess is like a small separate program within the main SAC program.

Signal_Stacking_Subprocess Manual which describes a subprocess for performing signal stacking with delays, traveltimes, and record section plots.

Program Design

SAC is a fairly portable code written in C. There are no differences between versions on different operaing systems.

Linux: 2.0.x and later

Mac OS X: 10.3 and later

Solaris: Solaris 5.8 and later

Windows/Cygwin

SAC handles graphics by including two different graphics devices in the code: