Three-dimensional Sensitivity Kernels for H/V Amplitude Ratio in Generalized Seismic Ambient Noise Interferometry

Abstract:

The H/V amplitude ratio (ellipticity) of Rayleigh waves is an unconventional surface wave observable that has been shown to exhibit enhanced sensitivity to Vp and density, compared to the traditional surface-wave dispersion measurements. 3-D sensitivity kernels for Rayleigh wave ellipticity have been recently developed for classical (e.g. earthquake-based) seismology but corresponding kernels specific to ambient noise cross-correlation waveforms, are currently not known in the published literature. We present sensitivity kernels for Rayleigh wave ellipticity under the framework of generalized interferometric theory for ambient noise.

Our approach extends a general treatment of cross correlations, without invoking relationships to the inter-station Green’s tensor, so that the kernels obtained within this framework best represent the sensitivities of realistic measurements made using ambient noise. We compute kernels with respect to Vp, Vs and density, using multicomponent cross-correlations computed for a 1-D medium by a semi-analytical method, and compare them to the corresponding classical kernels. Finally we discuss the potential of the cross-correlation kernels for multi-parameter (Vp, Vs, density) imaging of subsurface structure.