Explosion Source Modeling, Seismic Waveform Prediction and Yield Verification Research
Quarterly technical rept. 1 Feb-30 Apr 1976
SYSTEMS SCIENCE AND SOFTWARE LA JOLLA CA
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The theoretically computed and observed amplitudes of both the b and d maximum body wave phases for KASSERI agree to well within a factor of two at all of the five SDCS stations. Minor adjustments of the upper mantle model could improve the agreement at all the SDCS sites. Computations of the effect of material strength on teleseismic body wave amplitudes indicate that the amplitude of the b phase increases with decreasing strength the rate of increase being more rapid at lower levels of material strength. An additional effect is that the apparent period of the b phase increases rapidly with decreasing strength due to a shift in the corner frequency of the source spectrum. Further verification of the explosion source modeling code, SKIPPER, was achieved by comparison of free field ground motion calculations and observations for the PILEDRIVER and GASBUGGY explosions. In the case of PILEDRIVER, the exercise of a recently developed elastic wave propagation code verified that the observed PILEDRIVER RDP was not affected by reflected waves from the free surface or from layer interfaces in the source region.