On the reliability of direct Rayleigh-wave estimation from multicomponent cross-correlations

Seismic interferometry is routinely used to image and characterize underground geology. Thevertical component cross-correlations (C_ZZ) are often analysed in this process; although one canalso use radial component and multicomponent cross-correlations (C_RR and C_ZR, respectively),which have been shown to provide a more accurate Rayleigh-wave Green's function than C_ZZwhen sources are unevenly distributed. In this letter, we identify the relationship between themulticomponent cross-correlations (C_ZR and C_RR) and the Rayleigh-wave Green's functionsto show why C_ZR and C_RR are less sensitive than C_ZZ to non-stationary phase source energy.We demonstrate the robustness of C_RR with a synthetic seismic noise data example. Theseresults provide a compelling reason as to why C_RR should be used to estimate the dispersivecharacteristics of the direct Rayleigh wave with seismic interferometry when the signal-tonoiseratio is high.