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Numerical modeling of three-dimensional reverberation from elastic bottom facets.

1991; Acoustical Society of America; Volume: 90; Issue: 4_Supplement Linguagem: Inglês

10.1121/1.401154

1520-9024

Henrik Schmidt, Huaiyu Fan,

Geophysical Methods and Applications

The fundamental physics of the three-dimensional scattering and reverberation from bottom facets such as faults and extended diapirs is addressed by means of a numerical model based on a hybrid wave-number-integration–boundary-element (WI–BEM) approach. The bottom facet is assumed to be a two-dimensional inclusion in an otherwise horizontally stratified seismo-acoustic environment. The elastic wave equations can then be separated by applying the spatial Fourier transform in the axial direction, leading to an integral representation for the total field in terms of solutions to two-dimensional problems. These solutions are determined by a modified version of an existing WI–BEM model [P. Gerstoft and H. Schmidt, J. Acoust. Soc. Am. 89, 1629–1642 (1991)], incorporating the additional elastic boundary conditions and with the Green’s functions for the stratified seismo-acoustic environment determined by a three-dimensional version of safari [H. Schmidt and J. Glattetre, J. Acoust. Soc. Am. 78, 2105–2114 (1985)]. The WI–BEM approach inherently decomposes the total field into basic wave components, and the model is used to analyze the modal composition of the bistatic reverberation from a bottom diapir in a continental shelf environment, insonified by normal modes incident at oblique angles. For the same scenario the significance of scattering into seismic interface waves and horizontally polarized SH waves in the bottom is addressed. [Work supported by ONR and Alliant Techsystems.]