ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

1pAO9. Determination of physical properties of a porous seabed from reflection amplitude data by using the genetic algorithm.

Altan Turgut

Inst. of Marine Sci., METU, P.O. Box 28, Erdemli-Icel, Turkey

A global optimization technique, the genetic algorithm, is effectively used for the inversion of seabed properties from plane-wave reflection data. The seabed is modeled as a porous viscoelastic medium using Biot's theory and the plane-wave reflection coefficient is calculated using the analytical expressions derived by Stoll and Kan [J. Acoust. Soc. Am. 70, 149--156 (1980)]. A sensitivity analysis indicated that the plane-wave reflection shows strong dependency on the porosity, permeability, and shear modulus of the seabed. Inversion of these parameters is primarily attempted by assigning representative values to other Biot parameters which have secondary effects on the plane-wave reflection coefficient. Fast/slow compressional and shear-wave speeds, and density of the seabed, are also calculated using the inverted porosity, permeability, and shear modulus. An experimental technique by using a towed array and chirp signals is also discussed for effective and rapid surveying of the seafloor.