San Pedro (Chile volcano)

San Pedro
San Pedro with San Pablo volcano immediately right
Highest point
Elevation	6,155 m (20,194 ft)
Prominence	2,034 m (6,673 ft)[1]
Parent peak	Ojos del Salado
Listing	Ultra
Coordinates	21°53′16″S 68°23′29″W / 21.88778°S 68.39139°W / -21.88778; -68.39139[2]
Geography
San Pedro Chile
Parent range	Andes
Geology
Mountain type	Stratovolcano
Last eruption	1960[2]
Climbing
First ascent	16 July 1903; 120 years ago (1903-07-16) George Courty & Filemón Morales[3]

San Pedro is a Holocene composite volcano in northern Chile and at 6,155 metres (20,194 ft) in elevation one of the highest active volcanoes in the world. Part of the Chilean Andes' volcanic segment, it is part of the Central Volcanic Zone of the Andes, one of the four tracts of the Andean Volcanic Belt. This region of volcanism includes the world's two highest volcanoes Ojos del Salado and Llullaillaco. San Pedro, like other Andean volcanoes, was formed by the subduction of the Nazca Plate beneath the South America Plate. It has a neighbouring volcano, San Pablo, and is itself formed by two separate edifices usually known as the Old Cone and the Young Cone. These edifices are formed by rocks ranging from basaltic andesite over andesite to dacite and are emplaced on a basement formed by Miocene volcanic rocks.

The Old Cone was active over one hundred thousand years ago and was eventually truncated by a giant landslide that removed its northwestern side. Within the landslide scar lava flows and pyroclastic flows constructed the Young Cone as well as the lateral centre La Poruña. This volcano was glaciated during the Pleistocene and a large Plinian eruption occurred at the beginning of the Holocene. Some eruptions reportedly occurred during historical time; presently the volcano is fumarolically active.