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Nazca Plate
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The Nazca plate, shown in light blue
Full-size image showing all platesThe 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 under 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.
Seafloor spreading
Main articles: East Pacific Rise and Chile Rise
Yet another triple junction, the Chile Triple Junction,[1] 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.
[edit] Subduction
See also: Peru-Chile Trench
The eastern margin is a convergent boundary 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.
This triple junction is unusual in that it consists of a mid-oceanic ridge, the Chile Rise, being subducted under the South American Plate at the Peru-Chile Trench.
The subdubduction of Nazca plate under southern Chile has produced the largest recorded earthquake; the moment magnitude 9.5 1960 Valdivia earthquake.
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