Sedimentary Shear Modulus and Shear Speed Profiles from a Gravity Wave Inversion

Abstract

Experimental techniques and inverse methods have been established to extract sediment shear modulus vs depth profiles from measurements of wave-induced seabed motion. Seabed sediments are modelled as a quasi-static, ‘incompressible, layered elastic medium. An iterative eigenvalue expansion technique is used to extract the inverse. Using semi-empirical sediment models, it is possible to deduce sediment porosity and bulk density, and thus shear wave speed, from the shear modulus profile. The final results are supported by comparisons with borehole.stratigraphy logs and shear wave refraction results at a site on the New Jersey Shelf.