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

2pUW4. High-resolution cross-well tomography measurements.

Brian Rapids

Tokuo Yamamoto

Andrew Rogers

Murat Kuru

Geoacoustics Lab., Univ. of Miami, 4600 Rickenbacker Cswy., Miami, FL 33149

High-frequency/high-resolution marine cross-well tomography experiments have been conducted at several sites in the waters adjacent to South Florida. Frequencies ranged up to 15 kHz yielding nominal resolution of 10 cm for the tomographed cross sections. Experiments with several cross-sectional geometries determined by depth, range, source location, and receiver location were conducted, including orthogonal sections. These geometries allow determination of both two- and three-dimensional sediment compressional wave velocity structure. This structure may be evaluated for spectral content in both the two- and three-dimensional cases, a key indicator of sediment scattering strength. These spectra are computed for the experimental geometries and presented along side the calculated hydraulic structure. A companion paper being presented at this conference discusses the use of these wave-number spectra as input for modeling acoustic backscatter that was also measured at the cross-well tomography sites discussed here [Rogers et al., J. Acoust. Soc. Am.]. It is shown that cross-well tomography techniques employed on the ocean floor can provide excellent information for prediction of the acoustic backscattering strength. [Work supported by ONR.]