Quaternary Fault and Fold Database of the United States

Interactive Fault Map

This database contains information on faults and associated folds in the United States that demonstrate geological evidence of coseismic surface deformation in large earthquakes during the past 1.6 million years (Myr). At the time the Quaternary Fault and Fold database was established (1993), the Quaternary time period was defined as <1.6 Myr in the 1983 Geologic Time Scale, published in 1983. In 1999, it was updated to 1.8 Myr, and in 2009 it was revised to 2.6 Myr. Most recently, in 2018 it was revised again to 2.58 Myr, see GSA Geologic Time Scale.

In order to maintain a current and relevant dataset, effective January 12, 2017, the USGS will maintain a limited number of metadata fields that characterize the Quaternary faults and folds of the United States. Archived reports are accessible from the abbreviated record.

Fault Basics

offset in San Andreas fault
San Andreas fault zone, Carrizo Plains, central California. Photo by R.E. Wallace, USGS

About the Quaternary Faults and the National Seismic Hazard Maps

This database was used to create the fault-source characterization in the National Seismic Hazard Maps. For the hazard maps, both the fault surface trace and the metadata are simplified representations of the geometry and behavior of the fault, based on geologic interpretation.

Citation information - when using these data, please provide proper acknowledgment.