Quaternary Fault and Fold Database of the United States
This website contains information on faults and associated folds in the United States that are believed to be sources of M>6 earthquakes during the Quaternary (the past 1,600,000 years). Maps of these geologic structures are linked to detailed descriptions and references. Read our Factsheet for more information.
NOTE: This database is the source for faults used in the National Seismic Hazard Maps. The spatial representation of the faults in the hazard maps was simplified and critical fault parameters were assigned to produce the maps. To see the version of the faults used in the maps, go to the fault parameters section of the Hazard Maps website.
San Andreas fault zone, Carrizo Plains, central California. Photo by R.E. Wallace, USGS