Valerie J. Sahakian E.L. King Annemarie S. Baltay Sundstrom Alexis Klimasewski Tara A. Nye 2022 <p>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 (<i>Κ</i>₀), represents local site attenuation and effectively describes regional variations in ground motion [1]. However, estimates of <i>Κ</i>₀ are limited. We estimate the site parameter <i>Κ</i>₀ for 296 broadband and accelerometer stations in the San Francisco Bay area using 225 local events with M&gt;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 (<i>Κ</i>₀). We find that <i>Κ</i>₀ 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. <i>Κ</i>₀ estimates from this study will be useful to consider in future seismic hazard analyses and ground motion studies in the Bay Area.</p> application/pdf en Earthquake Engineering Research Institute Estimates of kappa in the San Francisco Bay area text