[S-CG45] Science of slow-to-fast earthquakes

[SCG45-41] Frequency and Non-Frequency Dependent DAS Strain-Rate Scaling Relations for S waves: an application in Mexico City

*Manuel J. Aguilar-Velazquez¹、Satoshi Ide¹、Mathieu Perton²、Zack J. Spica³ (1.Department of Earth and Planetary Science - The University of Tokyo、2.Instituto de Ingeniería - Universidad Nacional Autónoma de México、3.Earth and Environmental Sciences - University of Michigan)

キーワード：Distributed Acoustic Sensing (DAS), Scaling relations, Source information, Site effect characterization, Acceleration records and PGA

Distributed Acoustic Sensing (DAS) has gained popularity in seismological research for its ability to provide high-resolution spatially distributed (strain/strain-rate) seismic records. One of its applications is earthquake magnitude retrieval using either P- or S-wave records (i.e., scaling relations). In this study, we present DAS scaling relations for earthquakes recorded in Mexico City using S-wave strain-rate records. Three approaches were employed: 1) Non-frequency-dependent scaling relation based on earthquake magnitude, hypocentral distance, and the peak RMS amplitude observed in the records. 2) Frequency-dependent scaling relation between the strain-rate spectrum, hypocentral distance, and the acceleration source function in the frequency domain. Our results demonstrate that the magnitude/source and geometric spreading coefficients in both scaling relations are consistent with theoretical expectations (0.5 and -1.0, respectively). Additionally, the site effect term retrieved from both approaches aligns with the geological and infrastructural features near the DAS cables. In the third approach, we compare S-wave strain rate and acceleration records (recorded at nearby seismic stations) and show their proportional relationship, with the shallow S-wave velocity serving as the proportionality constant. All three approaches represent practical tools for earthquake magnitude estimation, site effect characterization, and/or peak ground acceleration retrieval.