Socompa

Socompa is a large stratovolcano (composite volcano) on the border of Argentina and Chile. It has an elevation of and is part of the Chilean and Argentine Andean Volcanic Belt (AVB). Socompa is within the Central Volcanic Zone, one of the segments of the AVB, which contains about 44 active volcanoes. It begins in Peru and runs first through Bolivia and Chile, and then Argentina and Chile. Socompa lies close to the pass of the same name where the Salta-Antofagasta railway crosses the Chilean border.

Most of the northwestern slope of Socompa collapsed catastrophically 7,200 years ago to form an extensive debris avalanche deposit. The Socompa collapse is among the largest known on land with a volume of and a surface area of ; its features are well-preserved by the arid climate. The deposit was at first considered to be either a moraine or a pyroclastic flow deposit, until the 1980 eruption of Mount St. Helens prompted awareness of the instability of volcanic edifices and the existence of large-scale collapses. There are large toreva blocks, which were left behind within the collapse crater. After the landslide, the volcano was rebuilt by the effusion of lava flows and much of the scar is now filled in.