Andean Volcanic Belt

The Andean Volcanic Belt is a chain of active and dormant volcanoes along the Andes, formed mainly where the Nazca and Antarctic plates descend beneath South America.

Andean subduction: The descent of oceanic plates beneath the South American Plate along the western margin of South America. This plate-boundary process supplies the belt’s magmas, but its geometry varies along the Andes.
South American Plate: A major tectonic plate carrying most of South America and parts of the adjacent Atlantic Ocean. The belt lies on its western margin, above the descending oceanic plates.
Ojos del Salado: A high stratovolcano on the Chile–Argentina border, widely recognized as the world’s highest active volcano. It is a prominent example from the Central Volcanic Zone.
Lahars: Fast-moving slurries of water and volcanic debris that travel down slopes and river valleys. Nevado del Ruiz’s 1985 eruption showed how lahars can devastate distant communities.
Flat-slab subduction: Subduction in which an oceanic plate descends at an unusually shallow angle beneath a continent. Flat-slab segments coincide with major gaps in volcanism along the Andes.
Nazca Plate: An oceanic tectonic plate beneath the eastern Pacific Ocean that moves beneath the South American Plate. Its subduction drives much of the belt’s volcanism in the Northern, Central, and Southern Andes.
Subduction zone: A region where one tectonic plate sinks beneath another into the mantle. The belt occupies the volcanic region above a long continental subduction zone.
Nevado del Ruiz: An active stratovolcano in Colombia whose 1985 eruption generated deadly lahars. Its eruption demonstrates how Andean volcanic hazards extend far beyond lava and ash.
Volcanic ash: Fine fragments of volcanic rock and glass blasted into the atmosphere during eruptions. Ash from Andean eruptions can disrupt aviation, agriculture, and settlements across borders.
Subduction erosion: The removal of material from an overriding plate by a subducting plate at a convergent margin. Its contribution to Andean crustal evolution and magma chemistry remains actively studied.

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