Incahuasi (Spanish pronunciation: [iŋkaˈwasi]; possibly from Quechua: inka Inca, wasi house)[3][4] is a volcanic mountain in the Andes of South America.

[5] Incahuasi lies on the border between Argentina and Chile,[2] close to Paso San Francisco.

[14] It has been suggested that a perpendicular chain of volcanoes including Ojos del Salado may be the consequence of the Juan Fernández Ridge subducting in the Peru–Chile Trench.

Between 9 and 6 million years ago, volcanic activity in the Maricunga Belt decreased and eventually ceased.

[19] With a height of 6,621 metres (21,722 ft), Incahuasi is the 12th-highest mountain in South America[20] and one of the world's highest volcanoes.

[22] The western and southwestern slopes of Incahuasi are dotted with lava domes,[2] which are more subdued than on other volcanoes in the region.

They have covered 10 square kilometres (3.9 sq mi) with lava[2] but they are probably an independent volcanic system, similar to other regional mafic volcanoes.

[29] Like many Andean volcanoes, Incahuasi has erupted andesite containing hornblende and pyroxene,[6] but also trachyandesite and trachydacite.

[6] The occurrence of such basic magmas in a volcanic setting dominated by dacites appears to be a consequence of local tectonics, which involve the extension of the crust compared to the compressional regime farther west.

[6] The mantle itself had been modified before by crustal material added by delamination of the lower crust and subduction erosion.

[26] This aridity is caused by the rain shadow effect of the Subandean Ranges, which block moisture from the Atlantic Ocean.

[36] Volcanic activity at Incahuasi may have continued into the Holocene, considering the young appearance of its eruption products[2] such as lava flows in the summit region and on the southern slopes; the old ages obtained by radiometric dating indicate an extinct volcano, although activity at Andean volcanoes is known to occur with long rest phases between eruptions (reaching one million years).

[38] The remoteness of the volcano means that future eruptions are unlikely to impact populated areas, however,[39] other than International Route CH-31 [es].