Over 70 Pleistocene or Holocene age volcanoes make up this volcanic belt, which on average has one eruption per year.
Tupungatito lies in proximity to the border between Argentina and Chile, 50 miles east of the Chilean capital Santiago.
It is a group of volcanic craters and a pyroclastic cone associated with a 5 kilometres (3.1 mi) wide caldera, and lies just southwest of the Tupungato volcano.
The caldera is filled with ice, and glaciers on the volcano are important sources of water for the Rio Maipo river and Santiago.
[5] There was speculation about the existence of a volcano in the Andes near Santiago already during the Colonial Era,[6] but only by 1890 was there a clear identification and even then it was frequently assumed that Tupungato instead was the only active edifice.
[8] Tupungatito is located in the Chilean Andes, 80 kilometres (50 mi) east from Santiago de Chile.
[9] Politically, it is part of the San Jose de Maipo municipality in the Metropolitan Region[10] where about 40% of all Chileans live.
[12] Tourism, mountaineering and hiking are the principal economic activities in the area; in addition, there are mines and hydropower plants in the valleys.
[14] The total volume of the volcano is estimated to be 30 cubic kilometres (7.2 cu mi),[10] and its flows are fresh and uneroded.
[18] The cold ice lacks internal water pockets and reaches a maximum thickness of 309 metres (1,014 ft).
[23] Arsenic pollution in the Maipo river system may originate from springs associated the volcanoes Tupungatito and San Jose.
[28] The volcano lies on a c. 50 kilometres (31 mi) thick crust, which together with the tectonic regime has influenced the composition of ascending magma.
[30] The volcano forms a volcanic group with Tupungato[18] and another peak, 6,000 metres (20,000 ft) high Nevado Sin Nombre.
[1] Tupungatito has erupted rocks ranging from basaltic andesite to dacite,[1] which define a potassium-rich calc-alkaline suite.
Processes involved are fractional crystallization, low degrees of partial melting and short periods of storage in magma chambers.
[18] Most precipitation occurs between May and September, when the north-south movement of the South Pacific High and the Westerlies lets frontal systems reach the area.
[40] Holocene activity added an explosive component[10] with Vulcanian and phreatomagmatic eruptions, which deposited pyroclastic materials around the volcano.
[33] The decline of the ice cover during the Holocene and an increased distance between glaciers and volcanic vents may have been responsible for this change in eruption style.
[50] The gases come from the magma, ultimately from the downgoing slab, and as they ascend they interact and mix with an overlying aquifer and a hydrothermal system.
[54] Intense eruptions could melt the ice on the volcano through the emission of incandescent rocks and pyroclastic flows, producing medium-sized or long lahars in the Quebrada de Tupungatito and Estero del Azufre valleys.
[10] Due to a combination between its relative proximity to population centres, high volume of ice and frequency of eruptions, a 2020 study ranked it the 4th most dangerous volcano on Earth in terms of lava-ice interactions.