A Spectral Method for Computing Complete Synthetic Seismograms.
Abstract
Much attention has been paid to the problem of the efficient computation of complete solution synthetic seismograms for flat, plane layered, laterally homogeneous elastic media and for high frequency bandwidths in the field of solid-earth geophysics. The only available methods for computing complete synthetic seismograms are computationally expensive and often suffer from numerical instabilities which limit their ranges of applicability. This report presents a new method based on a spectral representation of the solution of the elastic wave equation. Reformulating eigenvalue and eigenfunction computations avoids the numerical instabilities. A mode searching algorithm is developed which makes it possible to find large numbers of Rayleigh and Love dispersion curves efficiently and reliably. The locked mode approximation allows nearly complete synthetic seismograms to be computed using only the discrete part of the spectrum and using only normal modes with real eigen wave numbers. This is achieved by adding a high velocity cap layer to the bottom of the elastic model and by using phase velocity filtering to attenuate the spurious scattering caused by the cap layer. Comparisons of the results of the locked mode approximation with exact results obtained from other synthesis methods are presented and the limitations of the method are demonstrated and discussed. Examples of synthetic seismograms using the locked mode approximation are given along with a comparison of observed and synthetic seismograms.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1987
- Accession Number
- ADA187663
Entities
People
- Danny J. Harvey
Organizations
- University of Colorado Boulder