Description: The San Francisco-Pacifica Coast grid map was extracted from the California Geological Survey Map Sheet 58 that covers the entire state of California and originally published in May of 2011. It made use of several data layers such as Landslide Inventory, Geology, Rock Strength and Slope of varying scales and formats. For the statewide analysis of landslide susceptibility, the methodology of Wilson and Keefer (1985) was used in combining the rock strength and slope data layers as implemented by Ponti, el al. (2008) to create classes of landslide susceptibility. These classes express the generalization that on very low slopes, landslide susceptibility is low even in weak materials, and that landslide susceptibility increases with slope and in weak rocks.
The extracted grid map is composed of two data layers (Arc GRID Integer): sfcoast_sus- landslide susceptibility (1.16 MB) with cell value from 0 to 10 (low to high) representing susceptibility classes.
sfcoast_ls10-existing landslides in digital form (43.3 KB) with cell value of 10 (assigned to the highest susceptibility class by default).
Copyright Text: Wills C.J., Perez, F., Gutierrez, C., 2011, Susceptibility to deep-seated landslides in California: California Geological Survey Map Sheet 58 (http://www.conservation.ca.gov/cgs/information/publications/ms/Documents/MS58.pdf) Suggested citations: Graymer, R.W., Moring, B.C. Saucedo, G.J., Wentworth, C.M., Brabb, E.E., and Knudsen, K.L., 2006, Geologic Map of the San Francisco Bay Region: U.S. Geological Survey Scientific Investigation Map 2981. Ponti, D.J., Tinsley, J.C. III, Treiman, J.A., and Seligson, H., 2008, Ground Deformation, section 3c in Jones, L. M., Bernknopf, R., Cox, D., Goltz, J., Hudnut, K., Mileti, D., Perry, S., Ponti, D., Porter, K., Reichle, M., Seligson, H., Shoaf, K., Treiman, J., and Wein, A., 2008, The ShakeOut Scenario: U.S. Geological Survey Open-File Report 2008-1150 and California Geological Survey Preliminary Report 25 http://pubs.usgs.gov/of/2008/1150/. Spiker, E.C. and Gori, P., 2003, National landslide hazards mitigation strategy : a framework for loss reduction: U.S. Geological Survey Circular 1244, 56 p. Wieczorek, G.F., R.C. Wilson, R.C., and E.L. Harp, 1985. Map Showing Slope Instability during Earthquakes in San Mateo County, California. U.S. Geological Survey Miscellaneous Investigations Series Map I-1257-E. Wills, C.J., and Clahan, K.B., 2006, Developing a map of geologically defined site-conditions categories for California: Bulletin of the Seismological Society of America, V.96 p.1483-1501. Wilson, R.C., and Keefer, D.K., 1985, Predicting areal limits of earthquake-induced landsliding, in J.I. Ziony, editor, Evaluating earthquake hazards in the Los Angeles region – an earth-science perspective: U.S. Geological Survey Professional paper 1360, p.317-345. Wiegers, M.O., (unpublished), Landslide inventory map of the City and County of San Francisco, California: California Geological Survey, map prepared for the Seismic Hazard Zonation Program, 2001, scale 1:24,000. Thornburg, J., (unpublished), Landslide inventory map of the San Francisco South Quadrangle, Santa Mateo County, California; California Geological Survey, map prepared for the Seismic Hazard Zonation Program, 2005, scale 1:24,000.