Sensitivity analysis of rayleigh-wave ellipticity with application to near surface characterization

The joint inversion of surface-wave measurements and Rayleigh-wave ellipticity has gained popularity in recent years for near-surface soil characterization. The common approach is to use low-frequency, singlestation ellipticity data in conjunction with high-frequency dispersion measurements obtained employing small aperture arrays. A complete understanding of the diagnostic potential of ellipticity in such conditions can be assessed only with a complete sensitivity analysis. To this end, a new analytical method is presented for computing the sensitivity of Rayleigh-wave ellipticity with respect to the structural parameters of a layered elastic halfspace. This method employs a layer stacking procedure based on the subdeterminant formulation of the surface-wave forward problem and is numerically stable at high frequencies. The sensitivity of the ellipticity curve is then evaluated quantitatively with specific focus on near-surface examples and compared to the dispersion patterns and sensitivity of modal phase velocity. © (2015) by the European Association of Geoscientists & Engineers (EAGE).