NEHRP Clearinghouse
- Title
- Compressional and Shear Wave Velocity versus Depth in the San Francisco Bay Area, California: Rules for USGS Bay Area Velocity Model 05.0.0.
- File
- PB2006100099.pdf
- Author(s)
- Brocher, T. M.
- Source
- January 2005, 62 p.
- Identifying Number(s)
- USGS-OFR-05-1317
- Abstract
- This report summarizes and documents empirical compressional wave velocity (Vp) versus depth relationships for several important rock types in northern California used in constructing the new USGS Bay Area Velocity Model 05.0.0. These rock types include the Jurassic and Cretaceous Franciscan Complex (metagraywacke and greenstones), serpentinites, Cretaceous Salinian and Sierra granites and granodiorites, Jurassic and Cretaceous Great Valley Sequence, and older Cenozoic sedimentary rocks (including the La Honda basin). Similar relations for less volumetrically important rocks are also developed for andesites, basalts, gabbros, and Sonoma Volcanics. For each rock type I summarize and plot the data used to develop the velocity versus depth relationships. These plots document the existing constraints on the proposed relationships. This report also presents a new empirical Vp versus depth relation derived from hundreds of measuremnts in USGS 30-m vertical seismic profiles (VSPs) for Holocene and Plio-Quaternary deposits in the San Francisco Bay area.
- Keywords
- Velocity distribution; California; San Francisco Bay; Shear waves; Bays; Rock mechanics; Earthquakes