S002-0014
Compilation of Geologic and Seismic Velocity Characteristics at Advanced National Seismic System Strong Motion Accelerometer Sites

Monday, 7 December 2020
Poster
Garet Huddleston1, Lisa Schleicher2, Keith L Knudsen3, Lind S Gee3 and Jamison Haase Steidl4, (1)U.S. Geological Survey, Earthquake Science Center, Mountain View, CA, United States, (2)U. S. Geological Survey, Earthquake Science Center, Menlo Park, United States, (3)U.S. Geological Survey, Earthquake Science Center, Menlo Park, CA, United States, (4)University of California, Santa Barbara, Earth Research Institute, Santa Barbara, CA, United States
Abstract:
Near-surface site characteristics are critical for accurately modeling ground motion, which in turn influences seismic hazard analysis and design of critical infrastructure. Currently there are many strong motion accelerometers within the Advanced National Seismic System (ANSS) that are missing this information. We use a Geographic Information Systems (GIS) based framework to intersect the site coordinates of approximately 5,500 ANSS accelerometers located throughout the US and its territories with geology and velocity information. For this compilation, we consider: (1) surficial geology from digitized geologic maps, (2) measurements of the shear-wave velocity in the upper 30 m (VS30) at seismic stations (McPhillips et al., 2020; Yong et al., 2016), (3) three different VS30 proxies based on geology (Wills et al., 2015), terrain (Yong et al., 2012; Yong, 2016), and a hybrid approach that utilizes regional VS30 map insets or topographic slope based proxy mosaics (Allen and Wald, 2007; Thompson et al., 2014; Heath et al., 2020), and (4) VS30 values utilizing a combination of measurements and proxies from the Next Generation of Ground-Motion Attenuation Models (i.e., NGA-West2, NGA-East, and NGA-Subduction (Seyhan et al., 2014; Goulet et al., 2018; Bozorgnia et al., 2020)). We also explore including fundamental site periods (fpeak) at stations where waveform data are available and have been analyzed by the research community. This compilation will be populated on seismic station information webpages, like those of the Center for Engineering Strong Motion Data (strongmotioncenter.org), providing users the option to quickly obtain and utilize a variety of VS30 measurements, VS30 proxy-based estimates, and assigned National Earthquake Hazard Reduction Program (NEHRP) site classes. The collective availability of this information will improve our understanding of the ground motions recorded at ANSS accelerometers from both previous and future significant earthquakes. This additional station information will increase the usefulness of strong motion data and also improve ground motion models used in seismic hazard estimates.
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