Nazca Tectonic Plate: Galápagos Hotspot and Galápagos Rise
The Nazca Plate is an oceanic tectonic plate in the southeastern Pacific Ocean off the west coast of South America. Its subduction beneath South America is responsible for the Andes Mountains. The Galápagos hotspot is accountable for the Galápagos Islands.
The Nazca Plate (or Nasca* Plate), named after the Nazca region of southern Peru, is an oceanic tectonic plate in the southeastern Pacific Ocean off the west coast of South America.
It is bounded on the west by the Pacific Plate and to the south by the Antarctic Plate through the East Pacific Rise and the Chile Rise, respectively.
Motions around the plate include convergence towards the east with the South American Plate and divergence with the Antarctic, Pacific and Cocos plates. Convergence occurs when two plates are pushing into each other. Divergence occurs when plates pull away from each other.
A triple junction, the Chile Triple Junction, occurs on the seafloor of the Pacific Ocean off the Taitao and Tres Montes Peninsula on the southern coast of Chile. The Nazca Plate, the South American Plate, and the Antarctic Plate meet here.
The Nazca Plate is being subducted beneath most of the west coast of South America at a rapid rate of 80 - 100 mm (3 - 4 in) per year. The ongoing subduction along the Peru-Chile Trench is mainly responsible for the Andes Mountains, and its movement over several hotspots has created some volcanic islands.
Simplified sketch of the tectonic forces along most of the Andes
The Andean Volcanic Belt is a primary volcanic belt along the Andes mountain system in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed due to the Nazca and Antarctic Plate subduction underneath the South American Plate.
This active convergent margin is the most extended subduction zone globally, stretching about 7,500 km (4,600 mi). It produced the largest earthquake ever recorded, the M 9.5 Great Chilean Earthquake (Valdivia Earthquake), on May 22, 1960.
Nazca is a relatively young plate in terms of the age of its rocks and its existence as an independent plate, having been formed from the breakup of the Farallon Plate about 23 million years ago. The oldest rocks of the plate are about 50 million years old.
Map depicting the location of the Nazca Plate
Galápagos Hotspot / Galápagos Rise
The Galápagos hotspot is a volcanic hotspot responsible for the creation of the Galápagos Islands as well as three major aseismic ridge systems, which are on two tectonic plates.
The Galápagos Rise is a divergent boundary between the South American coast and the triple junction of the Nazca Plate, the Cocos Plate and the Pacific Plate.
The volcanically active Galápagos Islands exist on the Galápagos hotspot above the Galápagos Rise. The Galápagos Microplate is a small separate plate on the rise to the southeast of the triple junction.
Map illustrating the major tectonic plates of the world
* "Nazca" and "Nasca" are commonly used interchangeably, but generally, Nasca refers to the period and culture that inhabited this area, while Nazca describes the elements, such as the region, town, and river.