Using SAC

Introduction

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. Binary versions are available for Intel Mac and Linux, but SAC can be built from the source code for other computer operating systems. The source code is written in C. For further details regarding requirements to build and run SAC, see the README file that comes with the distribution.

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/hq/).

Thr Using SAC part of the SAC Users 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.

The Users Manual will be periodically updated to include new descriptions and to revise old ones. Please report any errors in this manual to the sac=help listserv: <sac-help@iris.washington.edu>. Although the version of the manual that comes with the binay or source distribution will be updated only when a new version comes out, the online version of the manual at <http://ds.iris.edu/files/sac-manual/> can be updated at any time.

Other Sections

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

Notation

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.