Quaternary Fault and Fold Database for 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. NOTE: This database is the source for faults used in the National Seismic Hazard Maps. These faults were altered and values added in order to use them in the modeling necessary 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. [Summary provided by the USGS.]