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Estimates of kappa in the San Francisco Bay area

September 20, 2022

Site characterization is a critical component of seismic hazards studies, especially in the development and use of ground motion models (GMMs). One such parameter, kappa (Κ0), represents local site attenuation and effectively describes regional variations in ground motion [1]. However, estimates of Κ0 are limited. We estimate the site parameter Κ0 for 296 broadband and accelerometer stations in the San Francisco Bay area using 225 local events with M>3.5. We first invert for kappa on the high-frequency slope of every record at a station, which represents full attenuation effects [2]. We then perform weighted regression of kappa versus distance to obtain expected kappa at the site (Κ0). We find that Κ0 varies extensively in the San Francisco Bay area, with values ranging from 0.004-0.113 s, thus representing the heterogeneous geologic conditions in the region. Κ0 estimates from this study will be useful to consider in future seismic hazard analyses and ground motion studies in the Bay Area.

Publication Year 2022
Title Estimates of kappa in the San Francisco Bay area
Authors Tara A. Nye, Valerie J. Sahakian, E.L. King, Annemarie S. Baltay, Alexis Klimasewski
Publication Type Conference Paper
Publication Subtype Conference Paper
Index ID 70247518
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center
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