Nazca Plate
Encyclopedia
The Nazca Plate, named after the Nazca
region of southern Peru
, is an oceanic tectonic plate in the eastern Pacific Ocean
basin off the west coast of South America
. The ongoing subduction
along the Peru-Chile Trench
of the Nazca Plate under the South American Plate
is largely responsible for the Andean orogeny
. The Nazca Plate is bound to the west to the Pacific Plate
and to the south with the Antarctic Plate
through the East Pacific Rise
and the Chile Rise
respectively. The movement of the Nazca Plate over several hotspots
has created some volcanic islands as well as east-west running seamount
chains that subduct under South America. Nazca is a relatively young plate both in terms of age of rocks and existence as independent plate.
, the Chile Triple Junction
, occurs on the seafloor of the Pacific Ocean
off Taitao
and Tres Montes Peninsula
at the southern coast of Chile
. Here three tectonic
plates meet: the Nazca Plate, the South American Plate
, and the Antarctic Plate
.
subduction zone under the South American Plate and the Andes Mountains, forming the Peru-Chile Trench
. The southern side is a divergent boundary
with the Antarctic Plate, the Chile Rise
, where seafloor spreading
permits magma
to rise. The western side is a divergent boundary with the Pacific Plate
, forming the East Pacific Rise
. The northern side is a divergent boundary with the Cocos Plate
, the Galapagos Rise
.
The subduction of the Nazca plate under southern Chile has a history of producing massive earthquakes including the largest ever recorded on earth, the moment magnitude
9.5 1960 Valdivia earthquake.
. 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
. 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
.
at its western end. It is being subducted under South America with the rest of the Nazca Plate.
experienced the earthquake of 1835
. It is expected that this area will be the epicenter of a major quake in the near future.Darwin Gap quake will shake Chile again http://www.newscientist.com/article/dn20048-darwin-gap-quake-will-shake-chile-again.html, New Scientist, 30 Jan 2011, accessed 8 Feb 2011.
Andes
Mountain Range. Deformation of the Nazca Plate even affects the geography of Bolivia
, far to the east (Tinker et al.). It was on the Nazca Plate that the 1994 Bolivia earthquake
occurred, measuring a magnitude MW of 8.2 and the strongest earthquake occurring deeper than 300 km.
Luckily, very few islands are there to suffer the earthquakes that are a result of complicated movements at these junctions. Juan Fernández Islands
is an exception.
to its north was the Farallon Plate
, which split in late Oligocene
times, about 22.8 Mya, a date arrived at by interpreting magnetic anomalies.
Nazca
Nazca is a system of valleys on the southern coast of Peru, and the name of the region's largest existing town in the Nazca Province. It is also the name applied to the Nazca culture that flourished in the area between 300 BC and AD 800...
region of southern Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, is an oceanic tectonic plate in the eastern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
basin off the west coast of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. The ongoing subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
along the Peru-Chile Trench
Peru-Chile Trench
The Peru-Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about 160 kilometres off the coast of Peru and Chile...
of the Nazca Plate under the South American Plate
South American Plate
The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....
is largely responsible for the Andean orogeny
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
. The Nazca Plate is bound to the west to the Pacific Plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....
and to the south with the Antarctic Plate
Antarctic Plate
The Antarctic Plate is a tectonic plate covering the continent of Antarctica and extending outward under the surrounding oceans. The Antarctic Plate has a boundary with the Nazca Plate, the South American Plate, the African Plate, the Indo-Australian Plate, the Scotia Plate and a divergent boundary...
through the East Pacific Rise
East Pacific Rise
The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate...
and the Chile Rise
Chile Rise
The Chile Rise or Chile Ridge is an oceanic ridge, a tectonic divergent plate boundary between the Nazca and Antarctic Plates. Its eastern end is the Chile Triple Junction where the Chile Rise is being subducted below the South American Plate in the Peru-Chile Trench...
respectively. The movement of the Nazca Plate over several hotspots
Hotspot (geology)
The places known as hotspots or hot spots in geology are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the mantle elsewhere. They may be on, near to, or far from tectonic plate boundaries. There are two hypotheses to explain them...
has created some volcanic islands as well as east-west running seamount
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
chains that subduct under South America. Nazca is a relatively young plate both in terms of age of rocks and existence as independent plate.
East Pacific and Chile Rise
A triple junctionTriple junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction a boundary will be one of 3 types - a ridge, trench or transform fault - and triple junctions can be described according to the types of plate margin that meet at them...
, the Chile Triple Junction
Chile Triple Junction
The Chile 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 American Plate, the Nazca Plate, and the Antarctic Plate...
, occurs on the seafloor of the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
off Taitao
Taitao Peninsula
The Taitao Peninsula is a westward projection of the mainland of Chile, with which it is connected by the narrow Isthmus of Ofqui, over which the natives and early missionaries were accustomed to carry their boats between the Moraleda Channel and Gulf of Penas...
and Tres Montes Peninsula
Tres Montes Peninsula
The Tres Montes 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 situated in Aisén Region close to the Chile Triple Junction of the Nazca, Antarctic and South American Plate....
at the southern coast of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
. Here three tectonic
Tectonics
Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...
plates meet: the Nazca Plate, the South American Plate
South American Plate
The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....
, and the Antarctic Plate
Antarctic Plate
The Antarctic Plate is a tectonic plate covering the continent of Antarctica and extending outward under the surrounding oceans. The Antarctic Plate has a boundary with the Nazca Plate, the South American Plate, the African Plate, the Indo-Australian Plate, the Scotia Plate and a divergent boundary...
.
Peru-Chile Trench
The eastern margin is a convergent boundaryConvergent boundary
In plate tectonics, a convergent boundary, also known as a destructive plate boundary , is an actively deforming region where two tectonic plates or fragments of lithosphere move toward one another and collide...
subduction zone under the South American Plate and the Andes Mountains, forming the Peru-Chile Trench
Peru-Chile Trench
The Peru-Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about 160 kilometres off the coast of Peru and Chile...
. The southern side is a divergent boundary
Divergent boundary
In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts which produce rift valleys...
with the Antarctic Plate, the Chile Rise
Chile Rise
The Chile Rise or Chile Ridge is an oceanic ridge, a tectonic divergent plate boundary between the Nazca and Antarctic Plates. Its eastern end is the Chile Triple Junction where the Chile Rise is being subducted below the South American Plate in the Peru-Chile Trench...
, where seafloor spreading
Seafloor spreading
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics....
permits magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
to rise. The western side is a divergent boundary with the Pacific Plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....
, forming the East Pacific Rise
East Pacific Rise
The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate...
. The northern side is a divergent boundary with the Cocos Plate
Cocos Plate
The Cocos Plate is an oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it.-Geology:...
, the Galapagos Rise
Galapagos Rise
The Galapagos Rise is a divergent boundary located between the South American coast and the triple junction of the Nazca Plate, the Cocos Plate, and the Pacific Plate. The volcanically active Galapagos Islands exist on the Galápagos hotspot above the Galapagos Rise...
.
The subduction of the Nazca plate under southern Chile has a history of producing massive earthquakes including the largest ever recorded on earth, the moment magnitude
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
9.5 1960 Valdivia earthquake.
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 ColombiaColombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to 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
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
. At each of these triple junctions an anomalous
Anomaly
Anomaly may refer to:-Astronomy and celestial mechanics :* In astronomy, an anomaly is a quantity measured with respect to an apsis, usually the periapsis...
microplate exists, the Galapagos Microplate
Galapagos Microplate
The Galapagos Microplate is a small tectonic plate off the west coast of South America near the Galapagos Islands. It differs from most other crustal plates in that it is rotating clockwise between three much larger crustal plates around it, the Nazca, Cocos and Pacific Plates...
at the northern junction and the Juan Fernandez Microplate
Juan Fernandez Plate
The Juan Fernández Plate is a small tectonic plate located at the triple junction between the Nazca Plate, Antarctic Plate and the Pacific Plate. It is moving in a clockwise direction. The Juan Fernández Islands of Chile are not carried on this plate as may be suggested by the name.-References:*...
at the southern junction. The Easter Island Microplate
Easter Plate
The Easter Plate is a small tectonic plate or microplate in the southeastern Pacific. The plate is bounded on the west by the Pacific Plate, and the east by the Nazca Plate. The entire plate is covered by the Pacific Ocean...
is a third microplate that is located just north of the Juan Fernandez Microplate and lies just west of Easter Island
Easter Island
Easter Island is a Polynesian island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian triangle. A special territory of Chile that was annexed in 1888, Easter Island is famous for its 887 extant monumental statues, called moai, created by the early Rapanui people...
.
Aseismic ridges
The Carnegie Ridge is a 1350-km-long and up to 300-km-wide feature on the ocean floor of the northern Nazca Plate that includes the Galápagos archipelagoGalápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
at its western end. It is being subducted under South America with the rest of the Nazca Plate.
Fracture zones
Darwin Gap is the area between the Nazca Plate and the coast of Chile, where Charles DarwinCharles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
experienced the earthquake of 1835
1835 Concepción earthquake
The 1835 Concepción earthquake occurred near the neighboring cities of Concepción and Talcahuano in Chile on February 20 at 15:30 local time and has an estimated magnitude of 8.2 Mfa or 8.1 Ml. The earthquake triggered a tsunami which caused the destruction of Talcahuano. A total of at least 50...
. It is expected that this area will be the epicenter of a major quake in the near future.Darwin Gap quake will shake Chile again http://www.newscientist.com/article/dn20048-darwin-gap-quake-will-shake-chile-again.html, New Scientist, 30 Jan 2011, accessed 8 Feb 2011.
Plate motion
The absolute motion of the Nazca Plate has been calibrated at 3.7 cm/yr east motion (88°), some of the fastest absolute motion 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 volcanicVolcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
Mountain Range. Deformation of the Nazca Plate even affects the geography of Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, far to the east (Tinker et al.). It was on the Nazca Plate that the 1994 Bolivia earthquake
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....
occurred, measuring a magnitude MW of 8.2 and the strongest earthquake occurring deeper than 300 km.
Luckily, very few islands are there to suffer the earthquakes that are a result of complicated movements at these junctions. Juan Fernández Islands
Juan Fernández Islands
The Juan Fernández Islands are a sparsely inhabited island group reliant on tourism and fishing in the South Pacific Ocean, situated about off the coast of Chile, and is composed of three main volcanic islands; Robinson Crusoe Island, Alejandro Selkirk Island and Santa Clara Island, the first...
is an exception.
Geologic history
The precursor of the Nazca Plate and the Cocos PlateCocos Plate
The Cocos Plate is an oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it.-Geology:...
to its north was the Farallon Plate
Farallon Plate
The Farallon Plate was an ancient oceanic plate, which began subducting under the west coast of the North American Plate— then located in modern Utah— as Pangaea broke apart during the Jurassic Period...
, which split in late Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
times, about 22.8 Mya, a date arrived at by interpreting magnetic anomalies.