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P- and S-Wave Suspension Velocity Logs in San Francisco Bay Region, Alameda, Santa Clara, and Sonoma Counties, California

Published by U.S. Geological Survey | Department of the Interior | Metadata Last Checked: August 25, 2025 | Last Modified: 20250411
This data release contains P- and S-wave velocity data from logs of nine wells in three large sedimentary basins in the San Francisco Bay region. The logs were collected between 2000 and 2006 for the U.S. Geological Survey under contract by R.A. Steller of GeoVision using an Oyo suspension logging system. Well depths range from 215 to 407 meters and sample spacing in the wells ranges from ½ to 2 meters; resultant Vs values range from less than 0.25 to 1.5 km/s, and Vp values range from less than 1.25 to 2.9 km/s. Five of the logs sample the Quaternary Santa Clara basin beneath the city of San Jose and the Santa Clara Valley, one well in the marshland north of the San Mateo Bridge samples the Quaternary South Bay basin beneath South San Francisco Bay and its margins, and three wells sample the Late Cenozoic Santa Rosa basin beneath the alluvial plain west of urban Santa Rosa. In addition to the velocity data files, the data release contains a plate that illustrates the velocity curves, a plate that illustrates the location and Quaternary geologic setting of the wells, a file describing the location and other details about the wells, and a brief text that describes the wells, the logs, and the character of the three sampled sedimentary basins with supporting literature from which the descriptions were compiled.

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