A Global Centroid Catalog of S‐Wave Microseisms: Insights Into the Role of Sedimentary Layers

Abstract

Although centroid catalogs of P‐wave microseisms have been established, a corresponding centroid catalog of S‐wave sources has been lacking. In this study, we constructed a centroid catalog of S‐wave microseisms. We generalized the autofocusing method to radial and transverse components to estimate the source locations of SV‐ and SH‐wave microseisms and applied it to three‐component Hi‐net records in the 0.1–0.25 Hz band from 2004 to 2024. Polarization analysis separated SV‐ and SH‐wave microseisms from P‐wave microseisms. We selected 442 reliable SV‐wave and 1,214 reliable SH‐wave microseisms based on the presence of P‐wave microseisms within a 1,000 km radius of the estimated centroid location. Comparison with the local sedimentary resonance period at the corresponding P‐wave centroid locations shows that both SV‐ and SH‐wave microseisms are preferentially detected in regions with thick sediments corresponding to sedimentary resonance periods of about 4–10 s. For SH‐only detections, S‐wave amplification relative to P‐waves shows no clear dependence on sedimentary resonance period. In contrast, reliable simultaneous detections of SV‐ and SH‐wave microseisms exhibit increasing amplification of both components with resonance period. This enhancement likely reflects scattering or leakage of trapped wavefields by basement roughness or basin edges. As the sedimentary resonance period approaches the dominant period of P‐wave microseisms, SV and SH energies become nearly equipartitioned, suggesting redistribution by sedimentary trapping and three‐dimensional scattering.