Body and Surface Wave Modeling of Observed Seismic Events
Semi-Annual technical rept. 1 May-31 Oct 1981
CALIFORNIA INST OF TECH PASADENA SEISMOLOGICAL LAB
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This research dealt with three main topics coupling of surface waves in laterally inhomogeneous source regions to teleseismic propagation paths, using regional waveforms to determine the source parameters of moderate-size earthquakes and the application of the Kirchoff-Helmholtz integral to seismic problems. First, the Representation Theorem is used to numerically evaluate the effectiveness of two commonly used algorithms for modeling Rayleigh wave propagation across lateral inhomogenities. Of the two, the conservation of lateral energy flux approximation most closely matches the maximum peak-to-peak amplitudes as seen through an LP-LRSM instrument. Next, a procedure for the systematic determination of source parameters from regional body waves is presented. A least squares inversion based on a cross-correlation of the data and squares inversion based on a cross-correlation of the data and synthetics is used to determine the fault mechanisms of a profile of the P sub nl synthetics and five earthquakes. The synthetics are for a western U.S. model which seems to be more than adequate for most continental regions.