Plate data: Bird (2003), PB2002, converted by Hugo Ahlenius, Nordpil (ODC-By 1.0). Land: Natural Earth (India POV).
The Cocos Plate is an oceanic plate in the eastern Pacific, off the coasts of Mexico and Central America. Bird (2003) counts it among the 14 large plates whose motion was described by the NUVEL-1A model, even though several of the small plates PB2002 adds, such as the Somali and Sunda Plates, cover more area.1 PB2002 places Cocos Island, off Costa Rica, on this plate.2
Its whole eastern edge is convergent in PB2002: it meets the North American, Caribbean and Panama Plates there, and every one of those boundaries is convergent along its whole length.1 To the north, the small Rivera Plate sits between the Cocos, Pacific and North American Plates. Bird marks a Rivera-Cocos orogen there, a zone where a simple plate model is not expected to be accurate.
Its boundaries with the Nazca and Pacific Plates are spreading ridges offset by transform faults. Where the three plates meet, Lonsdale (1988) found a microplate about 120 km wide at 2 degrees north on the East Pacific Rise, in a spot that had been expected to hold a simple triple junction. He named it Galapagos after the nearest land, although the Galapagos Islands lie about 1,100 km to the east (Bird 2003). USGS lists the Galapagos Islands among the hotspots that sit near the mid-ocean ridge system.
Bird also points to the Central and South America (CASA) geodetic study as an important new source of data here. It has benchmarks in five countries and on offshore islands on the Cocos, Nazca and Caribbean Plates, some of them measured since 1988.
Cocos Plate in numbers
Measured from its PB2002 outline, the Cocos Plate covers about 2.9 million km², or 0.6% of the
Earth's surface. That makes it number 17 by area of the 52 plates in the model.
It spans from 1°N to 19°N and from 106°W to 83°W.
Its edge is about 8,087 km long, mostly divergent:
48.4%divergentDivergent boundary. Plates pull away from each other and new crust forms between them. Source (3,913 km)
, 35.8%convergentConvergent boundary. Plates move toward each other and crust is destroyed as one plate dives under another. Source (2,894 km)
and 15.8%transformTransform boundary. Plates slide horizontally past each other. Crust is neither made nor destroyed. Source (1,280 km)
.
Along its boundaries it moves a mean 7.0 cm/yr relative to its neighbors, fastest against the Pacific Plate. Bird (2003)
Neighboring plates Neighbors. Plates that share a boundary with this plate. Most plate movement happens along these narrow zones between plates. Source
The Cocos Plate shares a boundary with 7 plates in PB2002, longest shared edge first.
The longest, about 3,033 km, is with the Nazca Plate; the shortest, about 105 km, is with the Rivera Plate.
