User's Manual of FD2: A Software Package for Modeling Seismological Problems with 2-Dimensional Linear Finite-Difference Method
Abstract
Fd2 is a software package developed at Teledyne Geotech Alexandria Laboratories (TGAL) during the past several years for generating synthetic seismograms and displaying the wavefields. This package consists of primarily a 2-dimensional 2nd-order explicit linear finite-difference (LFD) code. LFD method has the advantage that the solution contains all conversions and all orders of multiple scattering. It permits examinations of fairly general models with arbitrary complex variations in material properties and free-surface geometry. Furthermore, it does not require many assumptions commonly invoked in other theoretical approaches. The basic limitations to the LFD method or the finite- element method are the computational cost and memory requirements. These constrain the size of the grid and the number of time steps that can be calculated over a reasonable time frame. Our LFD code has a distinguishable feature in that it allows the inclusion o topographical free surface. This is particularly useful in modeling nuclear explosions buried in mountains. In this topical report, sample scripts are presented to illustrate the usage of fd2 and several supporting routines for plotting out the synthetics, generating 2- dimensional media, as well as the graphic visualization of wavefields. The algorithms for handling the boundary conditions of polygonal topography are reviewed in detail. Thus this topical report serves as both a programmer's guide and the user's manual. Numerical modeling, Finite-difference method, Free- surface topography, Seismic waves, Propagation, Scattering, Ripple firing.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 15, 1993
- Accession Number
- ADA275315
Entities
People
- Rong-song Jih