Compilation of <em>V</em><sub><em>S</em>30</sub> Data for the United States

For additional information, contact: Contact Information, Menlo Park, Calif. Office—Earthquake Science Center U.S. Geological Survey 345 Middlefield Road, MS 977 Menlo Park, CA 94025 http://earthquake.usgs.gov/ 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 Web sites. 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 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 VS30 compilation originated from publications directly reporting the work of field investigators. A small subset (less than 20 percent) of VS30 values was previously compiled by the USGS and other research institutions. Whenever possible, VS30 originating from these earlier compilations were crosschecked against published reports. 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 (2,141 sites), whereas 786 VS30 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 VS30 data (https://earthquake.usgs.gov/data/vs30/us/).