Analysis of Low Frequency Ground Motions Induced by Near-Surface and Atmospheric Explosions.
S-CUBED LA JOLLA CA
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This report describes the results of a preliminary analysis of the effects of variations in height of burst HOB on the low frequency ground motions induced by near-surface and atmospheric explosions. A mathematical model which can be used to simulate this component of the explosively generated ground motions is described and applied to the parametric investigation of the effects of HOB on a prototype 1 kt nuclear explosion detonated over a site model approximating the subsurface geology at Yucca Flat on the Nevada Test Site. These simulations indicate that although the details of the airblast loading vary considerably with HOB, the corresponding induced low frequency Rayleigh waves are essentially independent of HOB for HOB ranging from to 0 to 500m, at least for this site. The same theoretical model is also applied to the simulation of the low frequency ground motions to be expected from the proposed Pre-Direct Course HE experiment and a hypothetical surface burst test of the same yield at that site. It is shown that the surface waves predicted on the basis of the currently available subsurface model of the site are quite simple and pulse-like and also show little dependence on HOB over the range considered.