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New active-source shallow seismic (shear-wave and acoustic-wave) measurements were obtained at 18 prioritized seismic monitoring station locations in the north San Francisco Bay area to measure site-specific ground motion amplification effects, soil depth, depth to bedrock (Z1.0 Vs=1 km/s), calculate site specific velocity-depth profiles and Vs30, and develop NEHRP site classifications for each location. This study was led by Principal Investigators Jamey Turner, Cooper Brossy, and Daniel O’Connell and field data were acquired by Glendon Adams and Lincoln Steele. Seismic monitoring sites that recorded high PGA values during the M6.0 Napa earthquake, proximal to higher population densities, and sites recommended...
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About 280 kilometers of multichannel (common-depth-point) seismic reflection profiles were obtained in the central Mississippi River Valley by Geophysical Service Inc. and Western Geophysical Company under contracts with the U.S. Geological Survey. The specific area of the profiles is southeastern Missouri, northeastern Arkansas, and northwestern Tennessee. Geologically, the area is located in the northern part of the Mississippi Embayment.
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This data release provides a map of the time-averaged shear-wave velocity in the upper 30 m (Vs30) for California using the method described by Thompson and others (2014). There are two adjustments to the algorithm described by Thompson and others (2014), which is built on the geology-based Vs30 map by Wills and Clahan (2006). In this data release, we use the Wills and others (2015) updated geology-based Vs30 map. The second change is that we have adjusted the kriging procedure so that measured Vs30 values do not affect the predictions across distinctly different geologic units. July 2022 Update (ver. 2.0) Resolution is now 3 arcseconds instead of 7.5 arcseconds Fixed a code error that prevented some of the Vs30...
    map background search result map search result map Seismic Reflection Profiles in the Northern Mississippi Embayment An Updated Vs30 Map for California with Geologic and Topographic Constraints (ver. 2.0, July 2022) Seismic Reflection Profiles in the Northern Mississippi Embayment An Updated Vs30 Map for California with Geologic and Topographic Constraints (ver. 2.0, July 2022)