Mocho-Choshuenco

Geography & Climate

Mocho-Choshuenco is located in Chile, within the Southern Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 39.93° S, 72.03° W in the Southern Hemisphere, the volcano lies within a temperate climate zone. At 2,422 meters above sea level, Mocho-Choshuenco 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

Mocho-Choshuenco 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 Mocho-Choshuenco, 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

Mocho-Choshuenco has 2 recorded eruptions in the geological database, spanning from 1864 CE to 1937 CE. The most powerful recorded event was an explosive event producing ash plumes up to several kilometers in 1864 CE, reaching VEI 2 on the Volcanic Explosivity Index. These eruptions span roughly 73 years of volcanic history. The most recent eruption in 1937 CE places this volcano within the modern era of volcanological observation.

GVP Reference Summary

The compound Mocho-Choshuenco volcano is composed of two glacier-covered stratovolcanoes, located east of Lago Rinihué and SE of Lago Panguipulli and post-dating a 4-km-wide basaltic caldera. The small Choshuenco stratovolcano, constructed on the NW rim of the caldera, is late-glacial in age. A major Plinian eruption produced the Neltume Pumice about 10,300 years ago. The larger andesitic-to-dacitic El Mocho volcano, constructed within the caldera, is postglacial and has reported eruptions from 1864 and 1937. Additional craters and basaltic scoria cones are located on the flanks of Mocho-Choshuenco, primarily on the NE and SW sides.

— Smithsonian Institution, Global Volcanism Program