Lascar

Geography & Climate

Lascar is located in Chile, within the Central Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 23.37° S, 67.73° W in the Southern Hemisphere, the volcano lies within a tropical climate zone. At 5,592 meters above sea level, Lascar 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

Lascar 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 Lascar, 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

Lascar has 37 recorded eruptions in the geological database, spanning from 7250 BCE to 2023 CE. The most powerful recorded event was a cataclysmic eruption with ash columns reaching the stratosphere in 1993 CE, reaching VEI 4 on the Volcanic Explosivity Index. Notable eruptions include 2022 CE (VEI 3), 2006 CE (VEI 3), 2005 CE (VEI 3). With an average interval of roughly 251 years between eruptions over a span of 9,272 years, this is one of the more frequently active volcanoes in the database. This persistent activity suggests a robust and well-supplied magma system beneath the volcano. With eruptive activity as recently as 2023 CE, Lascar remains an actively monitored volcano.

Significance

With a maximum recorded VEI of 4, Lascar 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. Its 37 recorded eruptions make it one of the most prolific volcanoes in our database, reflecting a persistent and well-documented eruptive history that has provided volcanologists with extensive data for understanding eruption patterns and forecasting future activity. Given its recent activity, Lascar is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

Láscar is the most active volcano of the northern Chilean Andes. The andesitic-to-dacitic stratovolcano contains six overlapping summit craters. Prominent lava flows descend its NW flanks. An older, higher stratovolcano 5 km E, Volcán Aguas Calientes, displays a well-developed summit crater and a probable Holocene lava flow near its summit (de Silva and Francis, 1991). Láscar consists of two major edifices; activity began at the eastern volcano and then shifted to the western cone. The largest eruption took place about 26,500 years ago, and following the eruption of the Tumbres scoria flow about 9000 years ago, activity shifted back to the eastern edifice, where three overlapping craters were formed. Frequent small-to-moderate explosive eruptions have been recorded since the mid-19th century, along with periodic larger eruptions that produced ashfall hundreds of kilometers away. The largest historical eruption took place in 1993, producing pyroclastic flows to 8.5 km NW of the summit and ashfall in Buenos Aires.

— Smithsonian Institution, Global Volcanism Program