Oca–Ancón Fault System

Oca–Ancón Fault System
Falla Oca-Ancón
Location of the fault in Venezuela
Topographic map of northern Colombia showing the Oca Fault segment
Location	Northern South America
Coordinates	11°00′N 71°45′W / 11.000°N 71.750°W / 11.000; -71.750
Country	Colombia  Venezuela
Region	Caribbean
State	La Guajira Falcón, Zulia
Cities	Maracaibo
Characteristics
Range	Sierra Nevada de Santa Marta, Serranía del Perijá, Venezuelan Coastal Range
Part of	Andean faults
Segments	Oca, Ancón
Length	830 km (520 mi)
Strike	275 ± 7 (W-E)
Dip angle	Vertical to subvertical
Displacement	0.2–2 mm (0.0079–0.0787 in)/yr
Tectonics
Plate	South American
Status	Active
Earthquakes	1834
Type	Strike-slip fault
Movement	Dextral
Age	Late Pleistocene-Holocene
Orogeny	Andean

The Oca–Ancón Fault System (Spanish: Falla Oca-Ancón) is a complex of geological faults located in northeastern Colombia and northwestern Venezuela near the Caribbean Sea. The fault system is of right-lateral strike-slip type and extends for an approximate length of 830 km (520 mi).^[1][2][3] The Oca–Ancón Fault System is part of the diffuse boundary between the Caribbean plate and the South American plate.^[4] The movement rate of the Oca–Ancón Fault System is estimated at 2 millimetres (0.079 in) each year, more than most Venezuelan faults.^[2]

The vertical to subvertical Oca fault segment in the western part of the fault system has a length of 265 kilometres (165 mi), running west–east through La Guajira, Colombia. It forms the northern boundary of the Sierra Nevada de Santa Marta and cuts through the Serranía del Perijá continuing into Venezuela. The fault segment with a slip rate of 0.2 to 0.8 millimetres (0.0079 to 0.0315 in) per year has been active since the Late Pleistocene (~15,000 years ago) and its most recent activity has been registered in 1834.^[1]

• Audemard M., Franck A.; Singer P., André; Soulas, Jean-Pierre (2006), "Quaternary faults and stress regime of Venezuela" (PDF), Revista de la Asociación Geológica Argentina, 61 (4), Asociación Geológica Argentina: 480–491, retrieved 2015-11-24
• Audemard M., Franck A.; Singer P., André (1996a), "Active fault recognition in northwestern Venezuela and its seismogenic characterization: Neotectonic and paleoseismic approach", Geofísica Internacional, 35 (3): 245–255, doi:10.22201/igeof.00167169p.1996.35.3.460
• Audemard M., Franck A. (1996b), "Paleoseismicity studies on the Oca-Ancón fault system, northwestern Venezuela", Tectonophysics, 259 (1–3): 67–80, doi:10.1016/0040-1951(95)00144-1
• Paris, Gabriel; Machette, Michael N.; Dart, Richard L.; Haller, Kathleen M. (2000), Map and Database of Quaternary Faults and Folds in Colombia and its Offshore Regions (PDF), USGS, pp. 1–66, retrieved 2017-06-20