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Oca–Ancón Fault System

Coordinates: 11°00′N 71°45′W / 11.000°N 71.750°W / 11.000; -71.750
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Oca–Ancón Fault System
Falla Oca-Ancón
Map showing the location of Oca–Ancón Fault System
Map showing the location of Oca–Ancón Fault System
Location of the fault in Venezuela
Topographic map of northern Colombia showing the Oca Fault segment
LocationNorthern South America
Coordinates11°00′N 71°45′W / 11.000°N 71.750°W / 11.000; -71.750
Country Colombia
 Venezuela
RegionCaribbean
StateLa Guajira
Falcón, Zulia
CitiesMaracaibo
Characteristics
RangeSierra Nevada de Santa Marta, Serranía del Perijá, Venezuelan Coastal Range
Part ofAndean faults
SegmentsOca, Ancón
Length830 km (520 mi)
Strike275 ± 7 (W-E)
Dip angleVertical to subvertical
Displacement0.2–2 mm (0.0079–0.0787 in)/yr
Tectonics
PlateSouth American
StatusActive
Earthquakes1834
TypeStrike-slip fault
MovementDextral
AgeLate Pleistocene-Holocene
OrogenyAndean

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]

Oca fault segment

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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]

References

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  1. ^ a b Paris et al., 2000, p.9
  2. ^ a b Audemard et al, 2006
  3. ^ Audemard et al., 1996a
  4. ^ Audemard et al., 1996b

Bibliography

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  • 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