Inversion of sediment parameters in Biot parameter space

Abstract

Long range sediment tomography technique [Potty et al., J. Acoust. Soc. Am. 108, 973–986 (2000)] using explosive sources has been developed and applied to data from the Primer and ASIAEX experiments. This inversion scheme estimates the compressional wave speed and attenuation matching the individual modal arrival times, i.e., inversion is carried out in the geoacoustic parameter space. This inversion scheme is now modified to invert for parameters in the sediment physical property space. Using the Biot–Stoll model as the interface between sediment physical and geoacoustic spaces, few of the most sensitive Biot parameters are inverted for. A sensitivity analysis will be carried out to identify the most sensitive Biot parameters and they will be considered as unknowns. Broad band acoustic data from wide band sources (WBS) collected on a vertical line array in frequency range 10–400 Hz will be used for the inversion. The goal of this study is to identify the sediment type (sand, silt, sandy-silt, clay, etc.) along with some physical attributes qualifying its nature (soft, hard, etc.) and the thickness of layers. This will enable us to describe the sediment characteristics over a large area with minimum number of parameters. [Work supported by ONR.]