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.]