### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 4pUW10. Stochastic inhomogeneous volume model for fine-scale sediment
layering.

**Roger M. Oba
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*Naval Res. Lab., Stennis Space Center, MS 39529-5004
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An inverse relation of bottom loss to frequency was successfully modeled by
random fine-scale sediment layering [C. W. Holland and G. Muncill, J. Acoust.
Soc. Am. 94, 1609--1620 (1993)]. A computational method for propagation of the
Helmholtz equation in a water column with stochastic volume variation was
developed to compute average complex pressure field and average square of the
field numerically in a single pass. This model is revised for use in sediment
with uncertain layering, assuming negligible shear interaction. A uniform upward
refracting sediment has inclusions of fixed thickness, sound speed, and density,
but of uncertain vertical spatial distribution. The vertical interlayer spacing
is treated as a random variable with gamma distribution. This model also can be
used to isolate phenomena associated with density variation versus sound speed
variation. [Work supported by the Naval Research Laboratory and the Office of
Naval Research.]