The Peru–Chile Trench, also known as the Atacama Trench, is an

oceanic trench Oceanic trenches are prominent long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic tren ...

in the eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

, about off the coast of

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

and

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. It reaches a maximum depth of below sea level in Richards Deep () and is approximately long; its mean width is and it covers an expanse of some . The trench delineates the boundary between the

subducting Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

Nazca Plate and the overriding South American Plate.

Geology

The trench is a result of a convergent plate boundary, where the eastern edge of the oceanic Nazca Plate is being

subducted Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

beneath the continental South American Plate. The trench is also a part of the Chile Triple Junction, an unusual junction that consists of a

mid-oceanic ridge A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a dive ...

and the Chile Rise being subducted under the South American plate at the Peru-Chile Trench. Two seamount ridges within the Nazca Plate enter the subduction zone along this trench: the Nazca Ridge and the

Juan Fernández Ridge The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west–east direction from the Juan Fernández hotspot to the Peru–Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernánde ...

. From the Chile Triple Junction to

the trench is filled with of sediments, creating a flat bottom topography. Sediments are mainly

turbidite A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean. Sequencing Turbidites wer ...

s interspersed with oceanic deposits of clay, volcanic ash, and siliceous ooze. The Peru–Chile Trench, the

forearc Forearc is a plate tectonic term referring to a region between an oceanic trench, also known as a subduction zone, and the associated volcanic arc. Forearc regions are present along a convergent margins and eponymously form 'in front of' the vo ...

and the western edge of the central Andean plateau (Altiplano), delineate the dramatic "Bolivian

Orocline An orocline — from the Greek words for "mountain" and "to bend" — is a bend or curvature of an orogenic (mountain building) belt imposed after it was formed. The term was introduced by S. Warren Carey in 1955 in a paper setting forth how comp ...

" that defines the

Andean The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S l ...

slope of southern Peru, northern Chile, and Bolivia.

Oceanography

Most of the time, the

trade wind The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisph ...

s drive surface waters offshore near the equator, driving the Humboldt Current from the tip of southern Chile to northern Peru. This current is associated with upwelling of deep, nutrient-rich water off the coast of Peru. At times,

El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date ...

disrupts the usual wind pattern and lessens the upwelling. The consequent loss of nutrient causes

fish kills The term fish kill, known also as fish die-off, refers to a localized die-off of fish populations which may also be associated with more generalized mortality of aquatic life.University of Florida. Gainesville, FL (2005) ''Plant Management in Fl ...

Biology

In 2018, three new species of snailfish were discovered thriving in the depths of the Atacama Trench.

Associated seismicity

The subduction of the Nazca Plate below the South American Plate along the Chile-Peru Trench is associated with numerous earthquakes. Several of these earthquakes are notable for their size, associated tsunamis, and landslides. *1570 Concepcion earthquake: M_w ~8.3 *

1687 Peru earthquake The 1687 Peru earthquake occurred at 11:30 UTC on 20 October. It had an estimated magnitude of 8.4–8.7 and caused severe damage to Lima, Callao and Ica. It triggered a tsunami and overall about 5,000 people died. Tectonic setting The earth ...

: M_w ~8.7 *

1730 Valparaíso earthquake The 1730 Valparaíso earthquake occurred at 04:45 local time (08:45 UTC) on July 8. It had an estimated magnitude of 9.1–9.3 and triggered a major tsunami with an estimated magnitude of 8.75, that inundated the lower parts of Valparaíso. The ...

M_s ~8.7 * 1746 Lima–Callao earthquake: M_w ~8.7 * 1868 Arica earthquake: M_w ~9.0 *1877 Offshore Tarapaca, Peru: M_w ~8.3 *

1906 Valparaíso earthquake The 1906 Valparaíso earthquake hit Valparaíso, Chile, on August 16 at 19:55 local time. Its epicenter was offshore from the Valparaíso Region, and its intensity was estimated at magnitude 8.2 . This earthquake occurred thirty minutes after the ...

* 1942 Peru earthquake: M_w 8.2 event associated with a tsunami, the rupture dimensions and epicenter are similar to those of a 1996 earthquake *

1960 Valdivia earthquake The 1960 Valdivia earthquake and tsunami ( es, link=no, Terremoto de Valdivia) or the Great Chilean earthquake (''Gran terremoto de Chile'') on 22 May 1960 was the most powerful earthquake ever recorded. Various studies have placed it at 9.4– ...

: At M_w 9.5, the largest earthquake ever recorded on the earth * November 1960 Peru earthquake: This event had a long source duration, leading to a significant discrepancy between different moment calculation methods ( 6.75 vs 7.8) *

1970 Ancash earthquake The 1970 Ancash earthquake (also known as the Great Peruvian earthquake) occurred on 31 May off the coast of Peru in the Pacific Ocean at . Combined with a resultant landslide, it is the most catastrophic natural disaster in the history of Peru ...

: This M_w7.9 event triggered a landslide with large snow and ice components, killing ~68,000 people *

2001 southern Peru earthquake The 2001 southern Peru earthquake occurred at 20:33:15 UTC (15:33:15 local time) on June 23 with a moment magnitude of 8.4 and a maximum Mercalli intensity of VIII (''Severe''). The quake affected the Peruvian regions of Arequipa, Moquegua and ...

: M_w 8.4 *

2005 Tarapacá earthquake The 2005 Tarapacá earthquake occurred on June 13 at 22:44:33 UTC (18:44:33 local time). Its epicenter was located near Mamiña, in northern Chile about 125 km east-northeast of Iquique, affecting the Tarapacá Region and adjacent parts of Bo ...

2007 Tocopilla earthquake The 2007 Tocopilla earthquake occurred on November 14 at . Its epicenter was located between Quillagua and Tocopilla, affecting the Tarapacá and the Antofagasta regions in northern Chile. The earthquake had a moment magnitude of 7.7 and lasted a ...

* 2007 Peru earthquake: M_w 8.0 *

2010 Chile earthquake The 2010 Chile earthquake and tsunami ( es, Terremoto del 27F) occurred off the coast of central Chile on Saturday, 27 February at 03:34 local time (06:34 UTC), having a magnitude of 8.8 on the moment magnitude scale, with intense shaking l ...

: M_w 8.8 event associated with a tsunami * 2010 Pichilemu earthquake *

2014 Iquique earthquake The 2014 Iquique earthquake struck off the coast of Chile on 1 April, with a moment magnitude of 8.2, at 20:46 local time (23:46 UTC). The epicenter of the earthquake was approximately northwest of Iquique. The mainshock was preceded by a numb ...

2015 Illapel earthquake The 2015 Illapel earthquake occurred offshore from Illapel (Coquimbo region, Chile) on September 16 at 19:54:32 Chile Standard Time (22:54:32 UTC), with a moment magnitude of 8.3–8.4. The initial quake lasted between three and five minute ...

References

{{DEFAULTSORT:Peru-Chile Trench Geology of Chile Geology of Peru Landforms of Chile Landforms of Peru Lowest points of the World Ocean Natural history of South America Oceanic trenches of the Pacific Ocean Subduction zones

Geology

Oceanography

Biology

Associated seismicity

See also

References