Quetrupillan

Geography & Climate

Quetrupillan is located in Chile, within the Southern Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 39.50° S, 71.72° W in the Southern Hemisphere, the volcano lies within a temperate climate zone. At 2,360 meters above sea level, Quetrupillan rises above the surrounding terrain into montane or subalpine conditions. The elevation creates distinct ecological zones along its flanks, from forested lower slopes to exposed rocky terrain near the summit. 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

Quetrupillan 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 near Quetrupillan, 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 andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

Eruption History Summary

Quetrupillan has 5 recorded eruptions in the geological database, spanning from 11345 BCE to 1872 CE. The most powerful recorded event was a cataclysmic eruption with ash columns reaching the stratosphere in 35 CE, reaching VEI 4 on the Volcanic Explosivity Index. Notable eruptions include 255 CE (VEI 3), 35 CE (VEI 4), 10658 BCE (VEI 3). This eruption frequency indicates a moderately active volcanic system with periodic reawakenings.

Significance

With a maximum recorded VEI of 4, Quetrupillan has demonstrated the capacity for significant explosive eruptions that can impact regional aviation, agriculture, and communities tens of kilometers from the summit. VEI 4 eruptions produce ash columns reaching 15-25 kilometers into the atmosphere. With 5 recorded eruptions on file, Quetrupillan has enough documented activity to help scientists identify patterns in its eruptive behavior.

GVP Reference Summary

The late-Pleistocene to Holocene Quetrupillán Volcanic Complex is at the center of a group of three volcanoes, with Villarrica and Lanin, trending transverse to the Andean chain. Constructed within a large 7 x 10 km caldera, this glacier-covered volcano contains a 3.5-km-wide caldera and a truncated central cone. Work by Simmons et al. (2020) identified sixteen Holocene vents and their associated lavas around the lower flanks; compositions were dominantly trachyte, with one basaltic andesite eruption and two of trachyandesite. While each vent could represent a distinct eruption, and no absolute dates are available, Simmons et al. (2020) suggested that there had been about 10 eruptive periods associated with the vents, and that evidence of Holocene activity that had constructed the main cone had been removed by ice advances and retreats during the Little Ice Age. Four Holocene pumice lapilli deposits were identified by Fontijn et al. (2016) as originating from Quetrupillán, with compositions ranging from rhyolite to dacite. Other nearby volcanic features include a basaltic scoria cone 12 km NE, a rhyolitic lava dome on the S flank of the caldera, and both scoria cones and basaltic andesite lava flows about 15 km S. An eruption was reported in 1872 (Petit-Breuilh, pers. comm. 2004; Petit-Breuilh Sepúlveda, 2004), but Simmons et al. (2020) noted that there was no corroboration from multiple independent sources for such an event.

— Smithsonian Institution, Global Volcanism Program