Model parameter estimation of a porous seabed using in situ acoustic‐probe and chirp‐sonar reflection data.

Abstract

The velocity dispersion and frequency dependency of attenuation in marine sediments are two important measures that provide the ability to test the validity of geoacoustic models as well as to estimate physical properties from the acoustic data. A widely‐used Biot–Stoll theory for elastic‐wave propagation in porous marine sediments seems to predict a narrow band of dispersion that was measured only in well‐sorted granular marine sediments [A. Turgut and T. Yamamoto, J. Acoust. Soc. Am. 87, 2376–2382 (1990)]. Recent measurements in silty‐sand sediments show almost linear frequency dependency of attenuation and mild velocity dispersion within the 3–80 kHz frequency band. The newly measured attenuation and velocity dispersion curves are in good agreement with those predicted by an extended Biot theory for sediments with a distribution of pore sizes [T. Yamamoto and A. Turgut, J. Acoust. Soc. Am. 83, 1744–1751 (1988)]. Simultaneous measurements of in situ acoustic‐probe data and chirp‐sonar reflection data are also used to estimate the model parameters of the extended Biot model. [Work supported by the Office of Naval Research.]