### ASA 124th Meeting New Orleans 1992 October

## 5pPA8. Scattering by an obstacle embedded in a plane-stratified,
saturated, poro-elastic medium: Application to an obstacle in ocean sediments.

**Raymond Lim
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*Code N1120, Coastal Systems Station, Panama City, FL 32407-5000
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A transition matrix formalism for calculating the field scattered by a
bounded, three-dimensional obstacle buried in a plane-stratified, saturated,
poro-elastic environment is described. The formalism yields an exact solution
of the vector Biot equations, obeying all boundary conditions prescribed on the
layer and obstacle boundaries. This is obtained by combining the recently
derived free-field transition matrix for an obstacle in a porous medium [Kargl
and Lim, J. Acoust. Soc. Am. 90, 2371 (A) (1991)] with a generalization of
existing acoustic waveguide formalisms [see, for example, Hackman and
Sammelmann, J. Acoust. Soc. Am. 84, 1813--1825 (1988)]. The solution is
numerically implemented for a spherical obstacle buried in a layered ocean
sediment and insonified by an acoustic source in an overlying water
half-space.