Lonquimay

Geography & Climate

Lonquimay is located in Chile, within the Southern Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 38.38° S, 71.59° W in the Southern Hemisphere, the volcano lies within a temperate climate zone. At 2,832 meters above sea level, Lonquimay 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

Lonquimay 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 Lonquimay, 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

Lonquimay has 5 recorded eruptions in the geological database, spanning from 1853 CE to 1988 CE. The most powerful recorded event was a severe eruption capable of regional ash fall and pyroclastic flows in 1988 CE, reaching VEI 3 on the Volcanic Explosivity Index. Notable eruptions include 1988 CE (VEI 3), 1887 CE (VEI 3), 1853 CE (VEI 3). This eruption frequency indicates a moderately active volcanic system with periodic reawakenings. The most recent eruption in 1988 CE places this volcano within the modern era of volcanological observation.

Significance

With a maximum recorded VEI of 3, Lonquimay has produced eruptions capable of generating pyroclastic flows and significant ash fall in the surrounding area. While not among the largest eruptions globally, VEI 3 events pose serious hazards to local populations and can disrupt regional air travel. With 5 recorded eruptions on file, Lonquimay has enough documented activity to help scientists identify patterns in its eruptive behavior. Given its recent activity, Lonquimay is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

Lonquimay is a small, flat-topped, symmetrical stratovolcano of late-Pleistocene to dominantly Holocene age immediately SE of Tolguaca volcano. A glacier fills its summit crater and flows down the S flank. It is dominantly andesitic, but basalt and dacite are also found. The prominent NE-SW Cordón Fissural Oriental fissure zone cuts across the entire volcano. A series of NE-flank vents and scoria cones were built along an E-W fissure, some of which have been the source of voluminous lava flows, including those during 1887-90 and 1988-90, that extended out to 10 km.

— Smithsonian Institution, Global Volcanism Program