How do I find fault or hazard maps for California?
An online map of faults that includes California can be found in the Faults section of the Earthquake Hazards Program website. Choose the Interactive Fault Map, or download KML files and GIS shapefiles from the links on the page.
USGS seismic hazard maps, data and tools for California and other parts of the United States can be found in the Hazards section of the Earthquake Hazards Program website.
The California Department of Conservation, Division of Mines and Geology has a number of Geologic Maps and Data including:
- Geologic Map of California
- Alquist-Priolo Earthquake Fault Zone Maps
- Seismic Hazard Zone Maps
- Landslide Maps
- Watershed Maps
- Topographic Maps
What is the relationship between faults and earthquakes? What happens to a fault when an earthquake occurs?
Maps showing the potential for destructive mudflows in the wake of recent Southern California wildfires were made available to the public and emergency responders today by the U.S. Geological Survey (USGS).
The maps estimate the size of potential debris flows, commonly known as mudflows, and the areas that could be affected when rainfall begins on recently-burned areas.
The U.S. Geological Survey has a new website that offers a virtual tour of the Hayward fault.
At 6 p.m. Pacific Standard Time, the U.S. Geological Survey advised state and federal agencies about the continuing possibility of landslides and debris flows in seven counties of southern California. The counties are: San Diego, Riverside, Orange, San Bernardino, Ventura, Los Angeles, and Santa Barbara. Here is the advisory that was issued:
Three-dimensional perspective view of the likelihood that each region of California will experience a magnitude 6.7 or larger earthquake in the next 30 years (6.7 matches the magnitude of the 1994 Northridge earthquake, and 30 years is the typical duration of a homeowner mortgage).
Shaded relief image of the Santa Rosa area showing active faults (black lines) and the detailed rupture pattern of the Rodgers Creek Fault where it crosses central Santa Rosa (in red). The orange, bean-shaped area represents the dense, magnetic body of rock on the east side of the fault beneath Santa Rosa. This body of rock may be largely responsible for the pattern of...
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I saw on a map that I live in an area of "high liquefaction probability." What does that mean and can I do anything about it?
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Ground shaking triggered liquefaction in a subsurface layer of sand, producing differential lateral and vertical movement in a overlying carapace of unliquified sand and silt, which moved from right to left toward the Pajaro River. This mode of ground failure, termed "lateral spreading," is a principal cause of liquefaction-related earthquake damage.
The purpose of this map is to show the location of and evidence for recent movement on active fault traces within the Hayward Fault Zone, California. The mapped traces represent the integration of the following three different types of data: (1) geomorphic expression, (2) creep (aseismic fault slip),and (3) trench exposures.
Map of known active geologic faults in the San Francisco Bay region, California, including the Hayward Fault. The 72 percent probability of a magnitude (M) 6.7 or greater earthquake in the region includes well-known major plate-boundary faults, lesser-known faults, and unknown faults. The percentage shown within each colored circle is the probability that a M 6.7 or...