FINDIF : a software package to create synthetic seismograms by finite differences

Abstract

In order to study seismic wave propagation through laterally varying sea floor structures, a software package has been created to generate synthetic seismograms by finite differences. The elastic wave equation can be solved in two dimensions either for point sources in cylindrical coordinates or for line sources in rectangular coordinates. Vertical and radial variations of the elastic parameters are allowed. The package includes four programs. Input to the system consists of a short file containing parameter values to describe the model. The first program is used to initialize the system for the particular model being used. The source arrays and velocity matrices are each computed by a separate program. The final program, which actually carries out the finite difference calculations, includes six subroutines to implement different options based on alternative finite difference formulations. Two different kinds of output files are created by this program: one or more snap-shot files, and one time series file, which will usually include more than one series.