ABSTRACT

Slope-stability studies in the 1970s by the U.S. Geological Survey resulted in the publication of estimates of landslide damage, maps of estimated landslide abundance, slope maps prepared by photomechanical processes, photointerpretive maps of landslide, colluvial, and other surficial deposits, and maps of relative slope stability for the San Francisco Bay region. These studies documented that landslides were very abundant, caused significant numbers of deaths, and resulted in damage amounting to millions of dollars per year. Regional slope-stability maps prepared from bedrock geological maps, slope maps, and photointerpretive landslide inventory maps have been used by the Bay region community for many land-use planning decisions. Development in upland parts of the region that are underlain by unstable to marginally stable slopes generally cannot be undertaken at present without careful evaluation of slope stability based on published data and well-designed site investigations.