Rayleigh-Wave H/V via Noise Cross Correlation in Southern California

We study the crustal structure of southern California by inverting horizontal-to-vertical (H/V) amplitudes of Rayleigh waves observed in noise cross-correlation signals. This study constitutes a useful addition to traditional phase-velocity-based tomographic inversions due to the localized sensitivity of H/V measurements to the near surface of the measurement station site. The continuous data of 222 permanent broadband stations of the Southern California Seismic Network (SCSN) were used in production of noise cross-correlation waveforms, resulting in a spatially dense set of measurements for the southern California region in the 1–15 s period band. The fine interstation spacing of the SCSN allows retrieval of high signal-to-noise ratio Rayleigh waves at periods as low as 1 s, significantly improving the vertical resolution of the resulting tomographic image, compared to previous studies with minimum periods of 5–10 s. In addition, horizontal resolution is naturally improved by increased station density. Tectonic subregions including the Los Angeles basin and Salton trough are clearly visible due to their high short-period H/V ratios, whereas the Transverse and Peninsular Ranges exhibit low H/V at all periods. Electronic Supplement: Maps of horizontal-to-vertical (H/V) ratios and their standard deviation, and the count of H/V ratio measurements exceeding the signal-to-noise ratio requirements and tables of the numbers used for the maps, along with figures of inverted VS and a Markov chain Monte Carlo histogram.