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. 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)), (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)) (5) Regional liquefaction, subsurface and seismic site class data as available. This compilation will help populate 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.

VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30 data are sparse or not readily available for most areas. Where data are available, VS30 values are often assembled in assorted formats that are accessible from disparate and (or) impermanent Websites. To help remedy this situation, we compiled VS30 measurements obtained by studies funded by the U.S. Geological Survey (USGS) and other governmental agencies. Thus far, we have compiled VS30 values for 4,369 sites in the United States, along with metadata for each measurement from government-sponsored reports, online databases, and scientific and engineering journals. Most of the data in our VS30 compilation originated from publications directly reporting the work of field investigators. A subset consisting of 20 percent of VS30 values was previously compiled by the USGS and other research institutions. VS30 originating from these earlier compilations were crosschecked against published reports when clarification was needed. Both downhole and surface-based VS30 estimates are represented in our VS30 compilation. Most of the VS30 data are for sites in the western contiguous United States (3,128 sites); 682 VS30 values are for sites in the Central United States; 267 VS30 values are for sites in the Eastern United States and Puerto Rico; 15 VS30 values are for sites in Alaska; 30 VS30 values are for sites in Hawaii. The remaining 247 sites are in the vicinity of Vancouver, Canada.

VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30 data are sparse or not readily available for most areas. Where data are available, VS30 values are often assembled in assorted formats that are accessible from disparate and (or) impermanent Websites. To help remedy this situation, we compiled VS30 measurements obtained by studies funded by the U.S. Geological Survey (USGS) and other governmental agencies. Thus far, we have compiled VS30 values for 4,369 sites in the United States, along with metadata for each measurement from government-sponsored reports, online databases, and scientific and engineering journals. Most of the data in our VS30 compilation originated from publications directly reporting the work of field investigators. A subset consisting of 20 percent of VS30 values was previously compiled by the USGS and other research institutions. VS30 originating from these earlier compilations were crosschecked against published reports when clarification was needed. Both downhole and surface-based VS30 estimates are represented in our VS30 compilation. Most of the VS30 data are for sites in the western contiguous United States (3,128 sites); 682 VS30 values are for sites in the Central United States; 267 VS30 values are for sites in the Eastern United States and Puerto Rico; 15 VS30 values are for sites in Alaska; 30 VS30 values are for sites in Hawaii. The remaining 247 sites are in the vicinity of Vancouver, Canada.

The multi-period BSE-1E and BSE-2E response spectra for the 2023 ASCE 41 Standard are derived from the downloadable data files. For each site class, 5% in 50 year uniform hazard spectral accelerations and 20% in 50 year uniform hazard spectral accelerations are provided for 22 spectral periods.

The multi-period BSE-1E and BSE-2E response spectra for the 2023 ASCE 41 Standard are derived from the downloadable data files. For each site class, 5% in 50 year uniform hazard spectral accelerations and 20% in 50 year uniform hazard spectral accelerations are provided for 22 spectral periods.

The multi-period BSE-1E and BSE-2E response spectra for the 2023 ASCE 41 Standard are derived from the downloadable data files. For each site class, 5% in 50 year uniform hazard spectral accelerations and 20% in 50 year uniform hazard spectral accelerations are provided for 22 spectral periods.

The multi-period BSE-1E and BSE-2E response spectra for the 2023 ASCE 41 Standard are derived from the downloadable data files. For each site class, 5% in 50 year uniform hazard spectral accelerations and 20% in 50 year uniform hazard spectral accelerations are provided for 22 spectral periods.

The multi-period BSE-1E and BSE-2E response spectra for the 2023 ASCE 41 Standard are derived from the downloadable data files. For each site class, 5% in 50 year uniform hazard spectral accelerations and 20% in 50 year uniform hazard spectral accelerations are provided for 22 spectral periods.

The multi-period BSE-1E and BSE-2E response spectra for the 2023 ASCE 41 Standard are derived from the downloadable data files. For each site class, 5% in 50 year uniform hazard spectral accelerations and 20% in 50 year uniform hazard spectral accelerations are provided for 22 spectral periods.

The multi-period BSE-1E and BSE-2E response spectra for the 2023 ASCE 41 Standard are derived from the downloadable data files. For each site class, 5% in 50 year uniform hazard spectral accelerations and 20% in 50 year uniform hazard spectral accelerations are provided for 22 spectral periods.