The Phase-Screen Method for Elastic Wave and Seismic Discrimination
Abstract
The phase-screen method to compute elastic vector wave propagation in three-dimensional heterogeneous media is developed, accounting for the difference in phase velocities of the transverse and longitudinal polarizations. The method replaces the heterogeneous medium with a homogeneous one and a set of phase screens. Between the screens the displacement is propagated by the uniform elastodynamic wave equation. The phase of each polarization of the wave, accumulated from propagating in the z-direction, is corrected at the screens to account for inhomogeneities. Only forward propagation is included in the analysis. A criterion is derived to determine the number of phase screens to be used. The energy fluxes of the S and P waves are also computed. We find that energy conservation requires special consideration for application of the method to vector waves. The method is tested on a two-dimensional problem whose exact solution is also computed. The primary application of the method is to compute vector wave propagation in random media for the purpose of treaty monitoring. In particular, we demonstrate how P-S conversion and SH-SV ratios may be efficiently computed for realistic media by employing the phase-screen method on statistical modeling.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 15, 1989
- Accession Number
- ADA220771
Entities
People
- Gary D. Mccartor
- Mark D. Fisk