This line shapefile depicts the relative activity of faults in Monterey County, California. Fault rupture is a seismic hazard that affects structures sited above or nearby an active fault (fault showing movement within the past 11,000 years). The only known historically active fault in Monterey County is the San Andreas fault, which ruptured during the 1966 Parkfield earthquake. The State of California has not zoned other faults within Monterey County as active; however, other studies document Holocene activity on local faults. These include the offshore parts of the Navy and Chupines faults (McCulloch and Greene, 1989); the Tularcitos, Sylvan thrust, Hatton Canyon (Rosenberg and Clark, 1994); the Garrapata/Palo Colorado and Rocky Creek fault segments of the southern San Gregorio fault zone (Clark and Rosenberg, 1999); the San Gregorio fault offshore of Point Sur (Eittreim and others, 1998), and the Zayante/Vergeles fault (Coppersmith, 1979). Other faults such as the Reliz/Rinconada, the Sur fault zone, the Laureles, the Cachagua, and the Miller Creek faults show indications of late Pleistocene activity (750,000 to 11,000 years before present). Detailed work on these faults may show that they are more recently active than currently known. Most of the faults in Monterey County are classified as pre-Quaternary (latest movement more than 1,600,000 years before present). This classification is a result of a lack of information, rather than conclusive evidence as to the timing of fault movement because the majority of geologic mapping did not focus on the activity assessment of faults. Faults classified as pre-Quaternary should not necessarily be regarded as inactive. This layer is part of a collection describing Geology resources and constraints Monterey County, California.The purposes of this data set are to show the location of faults and to provide a comparison of relative fault rupture hazard for regional planning studies in Monterey County. This map does not take the place of fault-rupture hazard zones designated by the California State Geologist (Hart and Bryant, 1999).