The Cocos Plate is a young oceanic

tectonic plate Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

beneath 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 continen ...

off the west coast of

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

, named for

Cocos Island Cocos Island ( es, Isla del Coco) is an island in the Pacific Ocean administered by Costa Rica, approximately southwest of the Costa Rican mainland. It constitutes the 11th of the 13 districts of Puntarenas Canton of the Province of Puntarenas ...

, which rides upon it. The Cocos Plate was created approximately 23 million years ago when the

Farallon Plate The Farallon Plate was an ancient oceanic plate. It formed one of the three main plates of Panthalassa, alongside the Phoenix Plate and Izanagi Plate, which were connected by a triple junction. The Farallon Plate began subducting under the west ...

broke into two pieces, which also created the Nazca Plate. The Cocos Plate also broke into two pieces, creating the small

Rivera Plate The Rivera Plate is a small tectonic plate (a microplate) located off the west coast of Mexico, just south of the Baja California Peninsula. It is bounded on the northwest by the East Pacific Rise, on the southwest by the Rivera Transform Faul ...

. The Cocos Plate is bounded by several different plates. To the northeast it is bounded by the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

and the

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 borders ...

. To the west it is bounded 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 Iza ...

and to the south by the Nazca Plate. __TOC__

Geology

The Cocos Plate was created by

sea floor spreading Seafloor spreading or Seafloor spread 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. History of study Earlier theories by Alfred Wegener an ...

along 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 along ...

and the

Cocos Ridge Cocos may refer to: Geography * Cocos, Bahia, Brazil * Cocos, Quebradillas, Puerto Rico, a barrio * Cocos Island (disambiguation) ** Cocos (Keeling) Islands, a territory of Australia in the Indian Ocean *** Shire of Cocos, a local government are ...

, specifically in a complicated area geologists call the Cocos-Nazca spreading system. From the rise the plate is pushed eastward and pushed or dragged (perhaps both) under the less dense

, in the process called

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, the ...

. The subducted leading edge heats up and adds its water to the mantle above it. In the mantle layer called the

asthenosphere The asthenosphere () is the mechanically weak and ductile region of the upper mantle of Earth. It lies below the lithosphere, at a depth between ~ below the surface, and extends as deep as . However, the lower boundary of the asthenosphere is not ...

, mantle rock melts to make

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 natural sa ...

, trapping

superheated water Superheated water is liquid water under pressure at temperatures between the usual boiling point, and the critical temperature, . It is also known as "subcritical water" or "pressurized hot water". Superheated water is stable because of overpres ...

under great pressure. As a result, to the northeast of the subducting edge lies the continuous arc of

volcano 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 plates are ...

s —also known as the

Central America Volcanic Arc The Central American Volcanic Arc (often abbreviated to CAVA) is a chain of volcanoes which extends parallel to the Pacific coastline of the Central American Isthmus, from Mexico to Panama. This volcanic arc, which has a length of 1,100 kilometer ...

— stretching from

Costa Rica Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...

Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by H ...

, and a belt of earthquakes that extends farther north, into

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. The northern boundary of the Cocos Plate is the Middle America Trench. The eastern boundary is a

transform fault A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subductio ...

, the

Panama Fracture Zone The Panama Fracture Zone is a major, active right lateral-moving transform fault and associated inactive fracture zone which forms part of the tectonic boundary between the Cocos Plate and the Nazca Plate. It is part of the triple junction between ...

. The southern boundary is 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 ...

, the

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 ...

.Paul J. Grim, "Connection of the Panama fracture zone with the Galapagos rift zone, eastern tropical Pacific"
The western boundary is another mid-ocean ridge, the

. A hotspot under the Galapagos Islands lies along the Galapagos Rise. (''see'' Galapagos hotspot and Galapagos Microplate) The

north of the Cocos Plate is thought to have separated from the Cocos Plate 5–10 million years ago. The boundary between the two plates appears to lack a definite

, yet they are regarded as distinct. After its separation from the Cocos Plate, the Rivera Plate started acting as an independent microplate. The devastating 1985 Mexico City earthquake and the

2017 Chiapas earthquake The 2017 Chiapas earthquake struck at 23:49 CDT on 7 September (local time; 04:49 on the 8th UTC) in the Gulf of Tehuantepec off the southern coast of Mexico near the state of Chiapas, approximately southwest of Pijijiapan (alternately, sou ...

were results of the subduction of the Cocos Plate beneath the

. The devastating El Salvador earthquakes in January 2001 and February 2001 were generated by the subduction of this plate beneath the

References

External links

The volcanic arcMartin Meschede and Udo Barckhausen, "Plate tectonic evolution of the Cocos-Nazca plate"
reconstructing its geological evolution {{Central America plates Tectonic plates Geography of Central America Galápagos Islands Geography of Mexico Geology of the Pacific Ocean Geology of Central America Geology of Mexico