Pichilemu Fault Explained

Pichilemu Fault
Other Name:Falla de Pichilemu
Namedfor:Pichilemu
Pushpin Map:Chile
Pushpin Relief:1
Country:Chile
Region:Libertador General Bernardo O'Higgins
State:Cardenal Caro
Cities:Pichilemu
Coordinates:-34.3917°N -72°W
Length:40km (30miles)
Width:20km (10miles)
Depth:15km (09miles)
Strike:010
Dip:East
Plate:South American
Status:Active
Earthquakes:2010 Pichilemu (Mw 6.9 & 7.0)
Type:Reverse
Rockunit:Pichilemu metamorphic complex, Neogene sediments
Age:Late Paleozoic-recent
Orogeny:Andean

The Pichilemu Fault (Spanish; Castilian: Falla de Pichilemu),[1] also referred to as the Pichilemu-Vichuquén Fault (Falla de Pichilemu-Vichuquén),[2] is a Chilean geological fault, located in Libertador General Bernardo O'Higgins Region, some kilometers away from Pichilemu,[1] at a depth of 15km (09miles).[3] The fault is 40km (30miles) long and 20km (10miles) wide.[3]

Activity

The fault became reactivated after the February 27, 2010, Chile earthquake, and gave rise to the 2010 Pichilemu earthquake on March 11.[4] At first, it was not known if it was formed during the February earthquake, or if it was just reactivated;[5] however, according to University of Chile geologist José Cembrano, "[it] corresponds to a long-live fault (in a million years time) whose activity had not been detected before."[1] Ancient activity of the fault has been theorized to have occurred in the Late Paleozoic and Late Mesozoic. The reverse fault has a north-northeast to south-southwest strike and dips to the east.[6] [7]

"This is a new record that we have found, and it explains why Pichilemu is experiencing so many tremors," the director of the Seismological Service of the University of Chile, Sergio Barrientos told La Tercera on May 22, 2010.[3] "It is not a crack nor an opening. It's a landslide," Barrientos added.[3] [8]

The Pichilemu Fault, along with the San Ramón Fault, was as of 2011 being studied by geologists of the University of Chile.[1]

Notes and References

  1. Web site: LAS CINCO FALLAS GEOLÓGICAS MÁS IMPORTANTES QUE CHILE DEBE TENER EN CUENTA . Radio Polar . . April 20, 2011 . es . April 23, 2011.
  2. Web site: Structural overprint of a late Paleozoic accretionary system in north-central Chile (34°-35°S) during post-accretional deformation . Andean Geology . Arne P. Willner . Peter P. Richter . Uwe Ring . November 10, 2010 . January 2009.
  3. News: Pichilemu tiene falla geológica que genera oleada de réplicas en esa zona. Fernández. O.. May 22, 2010. La Tercera. es. October 30, 2010. Santiago, Chile. dead. https://web.archive.org/web/20120303085454/http://latercera.com/contenido/680_261687_9.shtml. March 3, 2012.
  4. News: Sismos en Chile se deben a falla geológica en Pichilemu. 杜璐 (Dulu). May 23, 2010. China Internet Information Center. es. October 30, 2010. China.
  5. News: Sismólogos advierten sobre la activación de fallas después del terremoto. Correa. Paula. Radio Universidad de Chile. Universidad de Chile. es. October 30, 2010. Santiago, Chile.
  6. Farías . M. . Comte . S. . Roecker . D. . Carrizo . D. . Pardo . M. . 2011 . Crustal extensional faulting triggered by the 2010Chilean earthquake: The Pichilemu Seismic Sequence . . 30 . 6010 . 1–11 . 10.1029/2011TC002888 . 2011Tecto..30.6010F . 10533/132113 . 130357954 . free .
  7. Muñoz Linford . Pamela Karina . 2015 . Caracterización sísmica del Antearco Marino en la zona epicentral del mega-terremoto del Maule 2010 . MSc. thesis . . 1–71 . es . 2018-06-03.
  8. News: Falla geológica sería la causante de la oleada de réplicas en Pichilemu. Leiva. Erika. May 22, 2010. El Tipógrafo. es. October 30, 2010. Rancagua, Chile.