Only two damaging earthquakes have occurred in the 83 years since. Stress relieved by the 1906 earthquake appears to have built up to a filure level again. Thus, severe earthquakes are likely to be more frequent in the next few decades than from 1906 to the present. The severe damage in SF and Oakland caused many to think the epicenter was in that area. However similarly vulnerable sites down around Palo Alto were not affected.
Fire commonly exacerbates the disaster of an earthquake.
Its principal effect was felt in the Marina district, where ruptured gas lines started many fires. San Francisco's emergency plan for fire-fighting water nearly failed, since most of the fireboats required to pump water out of the Bay had long ago been sent to the junkyard. Liquefaction Liquefaction is a ubiquitous phenomenon in wet soils when earthquake shaking occurs. Wet soils, particularly those made of artificial fill, have a substantial pore volume, largely filled with water. However, the grain to grain contacts provide the soil with its cohesion.