Research on seismic monitoring at regional distances. Final report, 30 June 1995-30 June 1997
We report two studies related to numerical modeling of seismic wave generation and propagation. In the first, we use a 2-D multiple multipole method to model seismic wave radiation from nuclear explosions in and near underground cavities. Our modeling results are used to interpret seismograms recorded during the Non-Proliferation Experiment (NPE), which occurred near a large complex of tunnels and cavities. Synthetic seismograms for a simplified NPE geometry correlate well with the observed S-wave energy generated at or near the source and, by including near receiver tunnels into our models, we obtain the observed coupling between the radial and transverse component. The second study demonstrates the advantages of a newly developed irregular grid modeling technique for seismic wave propagation in laterally varying media. A numerical example demonstrates that the technique is more accurate than a standard regular grid finite difference method for modeling the effects of irregular interfaces. We then show that the method can be applied to models with irregular free surface topography, suggesting that our new variable grid method may be a valuable alternative to existing finite difference free surface algorithms. We demonstrate the effect of irregular surface topography on regional wave propagation with a Middle East example.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Earth Resources Lab.
- OSTI ID:
- 620563
- Report Number(s):
- AD-A--340979/4/XAB; MIT--63575; CNN: Contract F19628-95-C-0091
- Country of Publication:
- United States
- Language:
- English
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