Incahuasi, Nevado de

Geography & Climate

Incahuasi, Nevado de is located in Chile-Argentina, within the Central Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 27.03° S, 68.30° W in the Southern Hemisphere, the volcano lies within a subtropical climate zone. At 6,638 meters above sea level, Incahuasi, Nevado de reaches well into the permanent snow and ice zone. Glaciers and snowpack on the upper slopes create the potential for lahars — destructive volcanic mudflows — during eruptions, as heat rapidly melts ice and snow. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Incahuasi, Nevado de sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Chile-Argentina near Incahuasi, Nevado de, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is dacite, an intermediate to silica-rich volcanic rock. This composition typically produces more viscous magma, leading to more explosive eruptions with ash columns and pyroclastic flows. Andesitic and dacitic magmas build pressure before erupting, which is why volcanoes with this rock chemistry are often associated with Plinian-style eruptions that can send ash tens of kilometers into the atmosphere and disrupt aviation across entire regions.

GVP Reference Summary

Nevado de Incahuasi is a complex volcanic massif that straddles the Chile-Argentina border ENE of Nevados Ojos del Salado volcano. Two stratovolcanoes occupy a compound 3.5-km-wide caldera, and Pleistocene lava domes are located on the W and SW flanks. The youngest stratovolcano is capped by a 1-km-wide crater, and dacitic lava flows radiate down the flanks. The fresh-looking morphology of the youngest products suggest a Holocene (González-Ferrán, 1995) or possible Holocene (de Silva 2007, pers. comm.) age. A dacitic lava dome partially fills an arcuate crater on the E flank of Incahuasi (which means "House of the Inca" in Quechua). Four pyroclastic cones are located 7 km to NE and produced basaltic andesite lava flows that cover an area of 10 km2.

— Smithsonian Institution, Global Volcanism Program