The Loma Prieta, California, earthquake of October 17, 1989

Abstract

This is an account of the effects of the most costly earthquake to hit the United States since 1906, which took place in the Santa Cruz Mountain segment of the San Andreas Fault, some 25 miles long. The southwest side moved 6 feet northwestward and 4 feet upward in relation to the northeastern side. It was thus rather different from typical San Andreas displacements and was also distributed over a wide band. Most of the damage occurred in areas of unconsolidated sand and mud. Detailed information of the shock, its extent, aftershocks and surface displacements are also given, with impressive illustrations of building damage, the effects of ground liquefaction, landslides and highway deformation. Some future dangers are emphasised, especially since the lessons that could have been learned from the 1906 earthquake have been ignored. -A.Scarth