Liquiñe-Ofqui Fault

The Liquiñe-Ofqui Fault is major geological fault that runs a length of roughly 1,200 kilometres (750 mi) in a NNE-SSW orientation and exhibits current seismicity.[1][2] It is located in the Chilean Northern Patagonian Andes. It is a dextral intra-arc strike-slip fault.[2] Most large stratovolcanoes of the Southern Volcanic Zone of the Andes are aligned by the fault which allows for the movement of magma and hydrothermal fluids.[2]

Liquiñe-Ofqui Fault
Falla de Liquiñe-Ofqui
Approximate extent of the Liquiñe-Ofqui Fault shown in red. Note that it is near parallel to the Peru-Chile trench, the coastline, the Chilean Coast Range and the Andes
EtymologyLiquiñe, Ofqui
Named byHervé et al.
Year defined1979
Country Chile
Characteristics
RangeAndes
Length1,200 km (750 mi)
Tectonics
PlateSouth American
StatusActive
Earthquakes1960 Valdivia earthquake aftershock, 2007 Aysén Fjord earthquakes
TypeIntra-arc strike-slip fault
MovementDextral
OrogenyAndean
Volcanic arc/beltSouthern Volcanic Zone

The fault crosses several transverse faults including the Mocha-Villarrica Fault Zone (MVFZ) and the Biobío-Aluminé Fault Zone.[2] The fault have had periods of ductile deformation associated to pluton emplacement be it either at great depths or by shallow intrusions.[3]

The forces that move the fault are derivative of the oblique subduction offshore Chile's coast. This leads to partition of deformation between the subduction zone, the fore-arc and the intra-arc region where the fault lies.[2] A portion of the fault in Aysén Region likely slipped (moved) in an aftershock a few weeks after the 1960 Valdivia earthquake.[4] This same portion slipped again in April 2007 causing earthquakes in Aysén Fjord, triggering landslides and a local tsunami.[4]

The fault name was coined by Francisco Hervé, I. Fuenzalida, E. Araya and A. Solano in 1979.[5] The fault itself was first inferred by Chilean government agent Hans Steffen around 1900 who referred to it as a "tectonic furrow" (Spanish: surco tectónico).[5]

References
  1. Lange, D.; Cembrano, J.; Rietbrock, A.; Haberland, C.; Dahm, T.; Bataille, K (April 2008). "First seismic record for intra-arc strike-slip tectonics along the Liquiñe-Ofqui fault zone at the obliquely convergent plate margin of the southern Andes". Tectonophysics. 455 (1–4): 14. Bibcode:2008Tectp.455...14L. doi:10.1016/j.tecto.2008.04.014. hdl:10533/139825.
  2. Pérez-Flores, Pamela; Cembrano, José; Sánchez-Alfaro, Pablo; Veloso, Eugenio; Arancibia, Gloria; Roquer, Tomás (2016). "Tectonics, magmatism and paleo-fluid distribution in a strike-slip setting: Insights from the northern termination of the Liquiñe–Ofqui fault System, Chile" (PDF). Tectonophysics. 680: 192–210. Bibcode:2016Tectp.680..192P. doi:10.1016/j.tecto.2016.05.016. Retrieved June 1, 2018.
  3. Adriasola, Alberto C.; Stockhert, Bernhard (2008). "Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)". Revista Geológica de Chile. 35 (1): 39–61. doi:10.4067/s0716-02082008000100002.
  4. Kanamori, Hiroo; Rivera, Luis (2017). "An Mw =7.7 slow earthquake in 1960 near the Ays´en Fjord region, Chile" (PDF). Geophysical Journal International. 211: 93–106. doi:10.1093/gji/ggx292. Retrieved March 29, 2019.
  5. Hauser, A. (1991). "Hans Steffen, precursor del concepto falla Liquiñe-Ofqui". Revista Geológica de Chile (in Spanish). 18: 177–179.

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