Liquefaction during 1906 San Francisco Earthquake

Liquefaction-induced ground failures caused major damage during the 1906 San Francisco earthquake. An analysis of published reports shows that lateral-spreading landslides were the most pervasive and most damaging type of ground failure associated with liquefaction. Bridges, roadways, pipelines, and buildings suffered considerable damage. Pipeline failures were particularly critical in San Francisco, cutting off the water supply to the city and thus indirectly contributing to the substantial post earthquake fire damage. Flood plain, deltaic, and loose sand fill deposits were particularly vulnerable to lateral spreading failure. Recent borehole data from four lateral spreading locations show that loose, saturated sand underlies each site at shallow depths. Flow landslides developed on several sandy slopes but did little damage because of sparse development in the affected areas. No clear evidence of bearing capacity failures beneath buildings was found; however, settlement of several embankments may have been a consequence of liquefaction. In several instances ground failures caused by liquefaction have recurred at the same location during successive large earthquakes.