Proxy‐BasedVS30Estimation in Central and Eastern North America

Abstract

Time‐averaged shear‐wave velocity in the upper 30 m of a site ( V S 30) is the most common parameter used to characterize seismic site response in ground‐motion models. However, in central and eastern North America (CENA), only 6% of the seismic recording stations that contributed data to the Next Generation Attenuation‐East (NGA‐East) project have measurement‐based V S 30 values. We describe a shear‐wave velocity ( V S ) measurement database for CENA that was compiled to support the development of proxy‐based methods for V S 30 estimation. Using this database, we develop a hybrid geology‐slope approach for V S 30 estimation that utilizes newly considered large‐scale geologic maps, the extent of Wisconsin glaciation, sedimentary basin structure, and 30 arcsec topographic gradient. Nonglaciated sites have relatively modest natural log dispersion of V S 30 ( σ ln V =0.36) relative to glaciated regions ( σ ln V =0.66), indicating better proxy‐based predictability of V S 30 for the former. Based on these findings, we provide estimates of natural log mean and standard deviation of V S 30 for NGA‐East recording stations in a station database, available in the Ⓔ electronic supplement to this article. [Electronic Supplement:][1] Updated Next Generation Attenuation‐East (NGA‐East) station database and central and eastern North America (CENA) V S measurement database. [1]: http://www.bssaonline.org/lookup/suppl/doi:10.1785/0120160101/-/DC1