4aUW1. Geoacoustic modeling using the Biot theory.

Session: Thursday Morning, December 5

Time: 8:05

Author: Robert D. Stoll
Location: Lamont--Doherty Earth Observatory, Palisades, NY 10964


Since its first application to geoacoustic modeling of the seafloor in 1970, the Biot theory has proved to be a powerful tool for studying the acoustic response of a wide variety of sediments. By modeling the sediment as a porous, viscoelastic medium filled with a viscous fluid, the effects of changes in frequency-dependent compressibility of various components and the influence of different local mechanisms causing energy loss may be studied in an integrated manner. Using the principle of viscoelastic correspondence, it is shown how a variety of local losses resulting from ``hidden degrees of freedom'' can be incorporated into the overall model using viscoelastic operators. In particular, modeling the response of fine-grained, high-porosity sediment with a ``cardhouse''-type structure is compared with the approach required to model coarser sediment with lower porosity such as sand. As another example, the influence of gas bubbles including bubble resonance effects is included in the overall response by defining the fluid compressibility to be a complex, frequency-dependent parameter. [Work supported by ONR, Code 321OA.]

ASA 132nd meeting - Hawaii, December 1996