The Nazca Plate or Nasca Plate, named after the
Nazca
Nazca (; sometimes spelled Nasca; qu, Naska) is a city and system of valleys on the southern coast of Peru. It is also the name of the largest existing town in the Nazca Province. The name is derived from the Nazca culture, which flourished in ...
region of southern
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 ...
, is an oceanic
tectonic plate 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 conti ...
basin off the west coast of
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...
. The ongoing
subduction
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, ...
, along the
Peru–Chile Trench
The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about off the coast of Peru and Chile. It reaches a maximum depth of below sea level in Richards Deep () and is approximately long; ...
, of the Nazca Plate under the
South American Plate is largely responsible for the
Andean orogeny
The Andean orogeny ( es, Orogenia andina) is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system along ...
. The Nazca Plate is bounded on the west by the
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate.
The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and I ...
and to the south by the
Antarctic Plate through the
East Pacific Rise
The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located alon ...
and the
Chile Rise
The Chile Ridge, also known as the Chile Rise, is a submarine oceanic ridge formed by the divergent plate boundary between the Nazca Plate and the Antarctic Plate. It extends from the triple junction of the Nazca, Pacific, and Antarctic plates ...
respectively. The movement of the Nazca Plate over several
hotspots
Hotspot, Hot Spot or Hot spot may refer to:
Places
* Hot Spot, Kentucky, a community in the United States
Arts, entertainment, and media Fictional entities
* Hot Spot (comics), a name for the DC Comics character Isaiah Crockett
* Hot Spot (Tra ...
has created some
volcanic islands
Geologically, a high island or volcanic island is an island of volcanic origin. The term can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs (which have often formed ...
as well as east-west running
seamount chains that subduct under
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sou ...
. Nazca is a relatively young plate both in terms of the age of its rocks and its existence as an independent plate having been formed from the break-up of the
Farallon Plate about 23 million years ago. The oldest rocks of the plate are about 50 million years old.
Boundaries
East Pacific and Chile Rise
A
triple junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of three types – a ridge (R), trench (T) or transform fault (F) – and triple junctions can b ...
, 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 ...
, occurs on the seafloor of the
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 conti ...
off
Taitao and
Tres Montes Peninsula
The Tres Montes Peninsula ( es, Península Tres Montes, English: ''Three Hills Peninsula'') is a southwestward projection of Taitao Peninsula which in turn connects to the mainland of Chile by the narrow Isthmus of Ofqui. The peninsula is situa ...
at the southern coast of
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 ...
. Here, three
tectonic plates meet: the Nazca Plate, the
South American Plate, and the
Antarctic Plate.
Peru–Chile Trench
The eastern margin is a
convergent 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 ...
subduction zone
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 ...
under the South American Plate and the
Andes Mountains
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 ...
, forming the
Peru–Chile Trench
The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about off the coast of Peru and Chile. It reaches a maximum depth of below sea level in Richards Deep () and is approximately long; ...
. The southern side is a
divergent boundary with the Antarctic Plate, the
Chile Rise
The Chile Ridge, also known as the Chile Rise, is a submarine oceanic ridge formed by the divergent plate boundary between the Nazca Plate and the Antarctic Plate. It extends from the triple junction of the Nazca, Pacific, and Antarctic plates ...
, where
seafloor spreading permits
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natura ...
to rise. The western side is a divergent boundary with the
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate.
The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and I ...
, forming the
East Pacific Rise
The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located alon ...
. The northern side is a divergent boundary with the
Cocos Plate
The Cocos Plate is a young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it. The Cocos Plate was created approximately 23 million years ago when the Farallon Plat ...
, the
Galapagos Rise.
The subduction of the Nazca plate under southern Chile has a history of producing massive
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...
s, including the largest ever recorded on earth, the
moment magnitude 9.5
1960 Valdivia earthquake.
Intraplate features
Hotspots
A second triple junction occurs at the northwest corner of the plate where the Nazca, Cocos, and Pacific Plates all join off the coast of
Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the ...
. Yet another triple junction occurs at the southwest corner at the intersection of the Nazca, Pacific, and Antarctic Plates off the coast of southern
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 ...
. At each of these triple junctions an ''
anomalous'' microplate exists, the
Galapagos Microplate at the northern junction and the
Juan Fernandez Microplate at the southern junction. The
Easter Island Microplate is a third microplate that is located just north of the Juan Fernandez Microplate and lies just west of
Easter Island
Easter Island ( rap, Rapa Nui; es, Isla de Pascua) is an island and special territory of Chile in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian Triangle in Oceania. The island is most famous for its nearl ...
.
Aseismic ridges
The Carnegie Ridge is a and up to feature on the ocean floor of the northern Nazca Plate that includes the
Galápagos archipelago at its western end. It is being subducted under South America with the rest of the Nazca Plate.
Fracture zones
The
Darwin Gap is the area between the Nazca Plate and the coast of
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 ...
, where
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
experienced the
earthquake of 1835. It is expected that this area will be the
epicenter of a major quake in the near future.
Plate motion
The absolute motion of the Nazca Plate has been calibrated at east motion (88°), one of the fastest absolute motions of any tectonic plate. The subducting Nazca Plate, which exhibits unusual
flat slab subduction, is tearing as well as deforming as it is subducted (Barzangi and Isacks). The subduction has formed, and continues to form, the
volcanic
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plat ...
Andes
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 ...
Mountain Range. Deformation of the Nazca Plate even affects the
geography
Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, an ...
of
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 ...
, far to the east (Tinker et al.). The
1994 Bolivia earthquake
The 1994 Bolivia earthquake occurred on June 9, 1994. The epicenter was located in a sparsely populated region in the Amazon jungle, about 200 miles from La Paz.
The Harvard CMT Project assigned it a focal depth of 647 km and a magnitude o ...
occurred on the Nazca Plate; this had a magnitude of 8.2
, which at that time was the strongest instrumentally recorded earthquake occurring deeper than .
Aside from the
Juan Fernández Islands
The Juan Fernández Islands ( es, Archipiélago Juan Fernández) are a sparsely inhabited series of islands in the South Pacific Ocean reliant on tourism and fishing. Situated off the coast of Chile, they are composed of three main volcanic ...
, this area has very few other islands that are affected by the earthquakes that are a result of complicated movements at these junctions.
Geologic history
The precursor of the Nazca Plate,
Juan de Fuca Plate, and the
Cocos Plate
The Cocos Plate is a young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it. The Cocos Plate was created approximately 23 million years ago when the Farallon Plat ...
was the
Farallon Plate, which split in the late
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but t ...
, about 22.8
Mya, a date arrived at by interpreting
magnetic anomalies. Subduction under the South American continent began about 140 Mya, although the formation of the high parts of the Central Andes and the Bolivian
orocline did not occur until 45 Mya. It has been suggested that the mountains were forced up by the subduction of the older and heavier parts of the plate, which sank more quickly into the
mantle
A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that.
Mantle may refer to:
*Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear
**Mantle (vesture), an Eastern Orthodox ve ...
.
See also
*
2010 Chile earthquake
*
Caribbean Plate
The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America.
Roughly 3.2 million square kilometers (1.2 million square miles) in area, the Caribbean Plate border ...
References
Bibliography
Extreme Science site: "A Lesson in Plate tectonics"The basics explained.
*Muawia Barazangi and Bryan L. Isacks, "Spatial distribution of earthquakes and subduction of the Nazca plate beneath South America" in ''Geology'' Vol. 4, No. 11, pp. 686–692
Abstract*Mark Andrew Tinker, Terry C. Wallace,
Susan L. Beck, Stephen Myers, and Andrew Papanikolas, "Geometry and state of stress of the Nazca plate beneath Bolivia and its implication for the evolution of the Bolivian orocline" in ''Geology'' 24(5), pp. 387–39
Abstract*Cahill, T. and B. Isacks (1992). "Seismicity and shape of the subducted Nazca plate." ''Journal Geophysical Research'' 97 (12)
*James, D. (1978). "Subduction of the Nazca plate beneath Central Peru." ''Geology'' 6 (3) pp 174–178
Martin Meschede and Udo Barckhausen, "Plate tectonic evolution of the Cocos-Nazca spreading center"
{{Authority control
Tectonic plates
Geology of Chile
Natural history of Oceania
Natural history of South America
Geology of the Pacific Ocean