Faults--Offshore of Bodega Head Map Area, California

This part of DS 781 presents data for faults for the geologic and geomorphic map of the Offshore of Bodega Head map area, California. The vector data file is included in "Faults_OffshoreBodegaHead.zip," which is accessible from http://pubs.usgs.gov/ds/781/OffshoreBodegaHead/data_catalog_OffshoreBodegaHead.html.

Onshore investigations indicate that this section of the San Andreas Fault onland has an estimated slip rate of about 17 to 25 mm/yr (Bryant and Lundberg, 2002). Emergent marine terraces at Bodega Bay record uplift rates associated with the fault system of about 0.1 mm/yr (Landis and others, 2004). The devastating Great 1906 California earthquake (M 7.8) is thought to have nucleated on the San Andreas Fault about 70 kilometers south of this map area offshore of San Francisco (e.g., Bolt, 1968; Lomax, 2005), with the rupture extending northward through the Offshore of Bodega Head map area to the south flank of Cape Mendocino.

Faults were primarily mapped by interpretation of seismic reflection profile data (see field activity S-15-10-NC). The seismic reflection profiles were collected in 2010.

References Cited

Bolt, B.A., 1968, The focus of the 1906 California earthquake: Bulletin of the Seismological Society of America, v. 58, p. 457-471.

Bryant, W.A., and Lundberg, M.M., compilers, 2002, Fault number 1b, San Andreas fault zone, North Coast section, in Quaternary fault and fold database of the United States: U.S. Geological Survey website, accessed April 4, 2013, at http://earthquakes.usgs.gov/hazards/qfaults.

Landis, P.S., Gardner, T.W., and Merritts, D.J., 2004, Deformation of marine terraces along the western edge of the North American Plate, Bodega Bay to the Russian River, CA: Geological Society of America Abstracts with Programs, South-Central Section, Paper 6-3.

Lomax, A., 2005, A reanalysis of the hypocentral location and related observations for the Great 1906 California earthquake: Bulletin of the Seismological Society of America, v. 95, p. 861-877.