High-resolution remote sensing of geoacoustic properties of the seabed by a buried OBS

Abstract

An entirely new geophysical inverse theory has been developed to remotely measure the shear modulus versus depth profile of the seabed sediments using the gravity wave induced seabed motion [Yamamoto and Torii, Geophys. J. R. Astron. Soc. 85, 413–431 (1986)]. From several experiments conducted in shallow water (4–135 m), shear modulus profiles were extracted down to 200-m sediment depths, and at a resolution of 1 m [e.g., Trevorrow et al., Geophys. J. R. Astron. Soc. (to be published)]. There is a unique relation between the shear modulus and the porosity of sediment at a given overburden pressure. The porosity versus sediment depth profile is uniquely determined from the shear modulus profile using this relation. Finally, Vp, Vs, Qp−1, Qs−1 versus sediment depth profiles are obtained through the Biot-Yamamoto theory [Yamamoto and Turgut, J. Acoust. Soc. Am. 83, 1744–1751 (1988)]. Comparisons between the BSMP remote sensing results and borehole data at five AMCOR and other geophysical borehole sites show excellent agreement. Prediction of transmission loss using BSMP geoacoustic data agrees very well with experiments conducted at the New Jersey Shelf. [Work supported by ONR Code 11250A.]