Rayleigh-wave multicomponent cross-correlation-based source strength distribution inversion. Part 1: Theory and numerical examples

Cross-correlation-based seismic interferometry is commonly used to retrieve surface-wave Green's functions from ambient seismic noise recordings. This approach requires that seismic sources are isotropically distributed in all directions around two receivers. However, this assumption is rarely valid in practice. Thus full-waveform inversion theory has recently been applied to seismic noise cross-correlation functions, functions that include both source and structure information. Source information (e.g. location or strength) is essential for accurate structure information estimation. In this paper, we explain physically two types of source sensitivity kernels: one derived from traveltime misfits and the other derived from waveform misfits. We use these kernels for source inversion and demonstrate the benefits of using multicomponent cross-correlations in this source estimation process.