Inversion of shear properties in ocean sediments from numerical Scholte wave

Shear properties in marine environment are important to be measured for the stability of sediments, the tomography of shallow layers, and the conversion of acoustic energy from water-borne into sea bottom. Although surface wave methods are widely used to determine the shear wave velocity profiles at sites, inversion methods of shear attenuation have to be tackled with other difficult problems. So, an inversion method by dispersion curves of surface wave is developed and tested with the numerical Scholte wave data. The method includes three steps: extract of dispersion curves from data, calculation of forward dispersion model, and linear inversion by match of them. To simultaneously estimate dispersion curve of velocity and attenuation, Prony's method is applied for multi-modes of surface wave. Based on the methods of finding complex roots, forward model of dispersion curves is calculated with so accuracy as to get reasonable Jacoby of inversion. Different to inversion of shear velocity, the effect of spread loss is considered and investigated for Scholte wave. The performance of inversion shear wave velocity and attenuation profiles in the upper sediment layers is also examined for multi-mode dispersion curves.