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 contin ...

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, 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 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 Pacif ...

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 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 and the Cocos Ridge, 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. The subducted leading edge heats up and adds its water to the mantle above it. In the mantle layer called the asthenosphere, 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 (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

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 to Guatemala, 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 subduct ...

, 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.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 East Pacific Rise. A hotspot under the Galapagos Islands lies along the Galapagos Rise. (''see'' Galapagos hotspot and Galapagos Microplate) The Rivera Plate 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 The 1985 Mexico City earthquake struck in the early morning of 19 September at 07:17:50 (CST) with a moment magnitude of 8.0 and a maximal Mercalli intensity of IX (''Violent''). The event caused serious damage to the Greater Mexico City area ...

and the 2017 Chiapas earthquake 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