The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench 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 contine ...

, 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 = Seal (emblem), National seal , national_motto = "Fi ...

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 eas ...

. 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 Nazca Plate and the overriding South American Plate.

Geology

The trench is a result of a

convergent plate boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a p ...

, 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 The Chile Triple Junction (or Chile Margin Triple Junction) is a geologic triple junction located on the seafloor of the Pacific Ocean off Taitao and Tres Montes Peninsula on the southern coast of Chile. Here three tectonic plates meet: the South ...

, an unusual junction that consists of a mid-oceanic ridge and the Chile Rise being subducted under the South American plate at the Peru-Chile Trench. Two

seamount A seamount is a large geologic landform that rises from the ocean floor that does not reach to the water's surface (sea level), and thus is not an island, islet or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise a ...

ridges within the Nazca Plate enter the subduction zone along this trench: the Nazca Ridge and the Juan Fernández Ridge. From the

to Juan Fernández Ridge the trench is filled with of sediments, creating a flat bottom topography. Sediments are mainly turbidites interspersed with oceanic deposits of clay, volcanic ash, and siliceous ooze. The Peru–Chile Trench, the forearc and the western edge of the central Andean plateau (Altiplano), delineate the dramatic "Bolivian Orocline" that defines the Andean slope of southern Peru, northern Chile, and

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

Oceanography

Most of the time, the trade winds 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 disrupts the usual wind pattern and lessens the upwelling. The consequent loss of nutrient causes fish kills.

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: 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 * 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: 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: 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 T ...

: M_w 8.4 * 2005 Tarapacá earthquake * 2007 Tocopilla earthquake *

2007 Peru earthquake The 2007 Peru earthquake, which measured 8.0 on the moment magnitude scale, hit the central coast of Peru on August 15 at 23:40:57 UTC (18:40:57 local time) and lasted two minutes. The epicenter was located south-southeast of Lima at a depth ...

: M_w 8.0 * 2010 Chile earthquake: M_w 8.8 event associated with a tsunami *

2010 Pichilemu earthquake The 2010 Pichilemu earthquakes ( es, link=no, Terremoto de Pichilemu de 2010), also known as the Libertador O'Higgins earthquakes, were a pair of intraplate earthquakes measuring 6.9 and 7.0 that struck Chile's O'Higgins Region on 11 March 201 ...

* 2014 Iquique earthquake *

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 min ...

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