Where it is and what it carries
The Nazca Plate covers about 16.1 million square kilometers, or 3.2% of Earth’s surface, in the eastern Pacific Ocean between the East Pacific Rise and the west coast of South America. It is an oceanic plate. Its only land is volcanic: most of the Galapagos Islands of Ecuador, Easter Island and the Juan Fernandez Islands of Chile all sit on it.
The plate is named after the Nazca region of southern Peru. It carries several raised ridges of thickened crust left by hotspots, including the Carnegie Ridge east of the Galapagos and the Nazca Ridge, which meets the trench off southern Peru.
What happens at its edges
The western edge is the East Pacific Rise, where the Nazca Plate spreads away from the Pacific Plate at about 14 cm/yr on average and up to about 15 cm/yr. That is among the fastest seafloor spreading anywhere on Earth. Two small rotating plates sit along this ridge, the Easter Plate and the Juan Fernandez Plate.
The northern edge is the Galapagos Spreading Center, where the plate separates from the Cocos Plate at about 5.6 cm/yr. The southern edge is the Chile Rise, a ridge broken by long transform faults, where it moves away from the Antarctic Plate at about 5.7 cm/yr. In the northeast, the Panama Fracture Zone forms a transform boundary with the Panama Plate at about 4 cm/yr.
The eastern edge is the 4,297 km Peru-Chile Trench, also called the Atacama Trench, where the Nazca Plate sinks beneath the South American Plate at about 7.8 cm/yr. The same subduction continues beneath the Altiplano Plate (about 6.5 cm/yr) and the North Andes Plate (about 5.7 cm/yr). This steady convergence is what builds the Andes.
History
The Nazca Plate formed about 23 million years ago, when the old Farallon Plate split into the Cocos and Nazca plates. Since then it has kept spreading in the west and subducting in the east, so its oldest crust is the part now entering the trench. Where the Nazca Ridge reaches Peru, the slab sinks at a shallow angle, and the Andes above it have very few active volcanoes.
Earthquakes and volcanoes
The dataset lists 32 earthquakes of magnitude 6.5 or larger on the Nazca Plate itself since 1900, none of magnitude 8. The largest are two M7.4 events off Chile, in 1960 off Araucania and in 2010 west of Lebu, both close to the zones of much larger quakes on the overriding plate. Most great subduction earthquakes, including the 1960 Valdivia (M9.5) and 2010 Maule (M8.8) earthquakes, have epicenters on the South American side of the trench.
The plate holds 18 volcanoes in the dataset. The most active are the shield volcanoes of the Galapagos, such as Fernandina (last eruption 2024), Wolf (2022) and Sierra Negra (2018). Others are submarine vents along the East Pacific Rise.