The
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 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. A triple junction occurs at the northwest corner of the plate where the Nazca, the Cocos, and the Pacific plates all join off the coast of Colombia. A second triple junction occurs at the southwest corner at the intersection with the Nazca, the Pacific, and the Antarctic plates off the coast of southern Chile. At each of these triple junctions an anomalous microplate exists, the Galapagos Microplate at the northern junction and the Juan Fernandez Microplate at the southern junction. The Easter Island Microplate is a third microplate that is located just north of the Juan Fernandez Microplate and lies just west of Easter Island.
Yet another triple junction occurs where the Nazca, Antarctic and South American plates meet. This triple junction has been considered to be related to the moment magnitude 9.5, 1960 megathrust earthquake known as the Great Chilean Earthquake.
Luckily, very few islands are there to suffer the earthquakes that are a result of complicated movements at these junctions. Juan Fernández Islands is an exception.
