Compilation of V_S30 Data for the United States

V_S30, the time-averaged shear-wave velocity (V_S) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. V_S30 is typically based on geophysical measurements of V_S derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, V_S30 data are sparse or not readily available for most areas. Where data are available, V_S30 values are often assembled in assorted formats that are accessible from disparate and (or) impermanent Web sites. To help remedy this situation, we compiled V_S30 measurements obtained by studies funded by the U.S. Geological Survey (USGS) and other governmental agencies. Thus far, we have compiled V_S30 values for 2,997 sites in the United States, along with metadata for each measurement from government-sponsored reports, Web sites, and scientific and engineering journals. Most of the data in our V_S30 compilation originated from publications directly reporting the work of field investigators. A small subset (less than 20 percent) of V_S30 values was previously compiled by the USGS and other research institutions. Whenever possible, V_S30 originating from these earlier compilations were crosschecked against published reports. Both downhole and surface-based V_S30 estimates are represented in our V_S30 compilation. Most of the V_S30 data are for sites in the western contiguous United States (2,141 sites), whereas 786 V_S30 values are for sites in the Central and Eastern United States; 70 values are for sites in other parts of the United States, including Alaska (15 sites), Hawaii (30 sites), and Puerto Rico (25 sites). An interactive map is hosted on the primary USGS Web site for accessing V_S30 data (https://earthquake.usgs.gov/data/vs30/us/).