Body and Surface Wave Modeling of Observed Seismic Events
Abstract
The research can be divided into three main topics, modeling the excitation of surface waves from complex source regions, body wave amplitudes and attenuation across North America, and a technique for separation of multimode dispersion and excitation of observed vertical Lg using arrays. In Section II theoretical explosion mechanisms for an all azimuth reversal of Rayleigh waves are presented. Linear code methods for modeling nonlinear source region phenomena and techniques for coupling near source phenomena into the surface wave generation such as vertical separation of source radiation, mixed path approximations, and the elastodynamic representation theorem are reviewed. In Section III, a broad band amplitude study of P and SH waves from deep South American events recorded at WWSN stations in the United States provides constraints on upper mantle variations in attenuation. The prevalant feature in the short and long period bands is that the SH amplitudes show the same regional variations as the P, with the regional variations of short periods being similar, but enhanced relative to the variations at long periods. In Section IV, it is shown that Rayleigh-type Lg propagation in a laterally homogeneous continental crust can be synthesized by adding only a few overtones at periods greater than 2 sec. Section V presents short period P wave amplitude from nuclear explosions in the Soviet Union recorded by WWSSN stations in the United States. A well defined amplitude pattern is obtained for each source region.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1980
- Accession Number
- ADA095690
Entities
People
- David G. Harkrider
- Donald V. Helmberger
- J. Bernard Minster
Organizations
- California Institute of Technology