This report describes the history of seismic activity at Parkfield, California, which is situated on the San Andreas Fault. It points out that moderate-size earthquakes have occurred on the Parkfield section of the San Andreas fault at fairly regular intervals, and that the earthquakes may have been 'characteristic' in the sense that they occurred with some regularity (mean repetition time of about ... Full description.

In response to the Nisqually earthquake of 2001, the Washington State Division of Geology and Earth Resources (DGER) developed two types of earthquake hazard maps for every county in the state: liquefaction susceptibility maps, which outline areas where water-saturated sandy soil loses strength during earthquake shaking, and National Earthquake Hazards Reduction Program (NEHRP) site class maps, which ... Full description.

These Frequently-Asked-Questions and answers describe some of the effects of earthquakes. Some of the topics covered include ground shaking, surface faulting, ground failure, and tsunamis. Full description.

This photograph shows the damage to the City Hall in Santa Rosa, California that was caused by the San Francisco Earthquake that occurred on April 18, 1906. Full description.

This photograph shows the damage to the Old City Hall in San Francisco, California, that was caused by the San Francisco Earthquake that occurred on April 18, 1906. Full description.

This photograph shows the trace of a fault (in trench phase) as it passes beneath a barn. The trace developed during the April 18, 1906 San Francisco Earthquake. The location is the Skinner Ranch, near Olema, Marin County, California. Full description.

Users can access interactive mapping and Geographic Information Systems (GIS) data, and view or download maps and reports on California's most prominent earthquake hazards. These maps are intended to help avoid damage resulting from earthquakes and are used by cities and counties to regulate development and by property owners selling property within areas where seismic hazards have been identified. ... Full description.

This reference explains the phenomenon of soil liquefaction, a common cause of damage to man-made structures that occurs during earthquakes. Students can read an explanation of how the water in wet soils exerts a pressure on the soil particles that influences how tightly the particles themselves are pressed together, causing the soil to lose strength. The text is accompanied by animations that show ... Full description.

This map shows estimated Modified Mercalli Intensity (MMI) values for the City of San Francisco and the eight counties of the Greater Bay Area, in a scenario based on the 1906 earthquake along the San Andreas fault. The 430 kilometers of fault rupture included several segments during one massive earthquake. Links are supplied to more detailed maps of the cities of Rohnert Park, Pittsburg, Antioch, ... Full description.

This report describes the relationship between shaking intensity of earthquakes and the nature of the geologic materials in the San Francisco Bay area. In general, deep, loose sediments such as bay mud, beach, dune, and stream deposits, and man-made fill are more susceptible to shaking than are harder materials such as granite. It also points out that the majority of development in the Bay area is ... Full description.