Modeling Regional Seismic Waves From Underground Nuclear Explosion
Abstract
Two main topics are presented: the effects of ocean continent transition zones on L - g waves; and modeling regional Love waves with 2-D velocity structures. Hybrid regional and teleseismic SH mode sum seismograms are produced after propagation through a regional transition zone or other heterogeneity that exists as part of a longer, mostly plane-layered, path. In particular the effects of ocean continent transition regions of geometry for propagation along a partially oceanic path is a most a factor of four. Extending the oceanic path length changes this factor to at most 6. This is inadequate to explain the observed attenuation of Lg. Thus, additional effects, must be considered to provide a complete explanation of the attenuation of Lg. Long period seismograms recorded at Pasadena of earthquakes occurring along a profile to Imperial Valley are studied in terms of source phenomena versus path effects. Some of the events have known source parameters, determined by teleseismic or near-field studies, and are used as master events in a forward modeling exercise to derive the Green's functions that describe the propagation effects along the profile. Both timing and waveforms of records are matched by synthetics calculated from 2-dimensional velocity models. The best 2-dimensional section begins at Imperial Valley with a thin crust containing the basin structure and thickens towards Pasadena.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 09, 1988
- Accession Number
- ADA208525
Entities
People
- David G. Harkrider
- Donald V. Helmberger
- Robert W. Clayton
Organizations
- California Institute of Technology