### ASA 126th Meeting Denver 1993 October 4-8

## 1pUW10. Elastic wave scattering by an elliptical inclusion in a
fluid-saturated porous medium.

**Boris Gurevich
Ada P. Sadovnichaja
Sergei L. Lopatnikov
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*VNII Geosystem, Moscow, Russia
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**Sergei A. Shapiro
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*Geophysical Institute, University of Karlsruhe, Hertzstr. 16, 76187
Karlsruhe, Germany
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The problem of the scattering of an elastic wave by a small (compared to
the wavelength of the fast compressional wave) elliptical porous inclusion
placed in another fluid-saturated porous medium is studied using the Born
approximation. The mechanical behavior of both host and inclusion materials is
described by the low-frequency version of Biot's theory. Explicit formulas for
the amplitudes of the scattered normal compressional and shear waves and of
Biot's slow compressional wave are obtained. The effectiveness of Biot's slow
wave generation depends essentially on the ratio of the wavelength of the slow
compressional wave to the inhomogeneity size. For large values of this ratio
the results agree with the earlier low-frequency results [J. G. Berryman, J.
Math. Phys. 26, 1408--1419 (1985)] derived for a spherical inclusion. In the
opposite case new results are obtained. They are used to estimate the effective
velocity and attenuation of the normal compressional wave in a porous medium
containing randomly distributed inclusions. The frequency dependence of the
attenuation is consistent with the results for randomly layered porous
materials.