Purico Complex

Geography & Climate

Purico Complex is located in Chile, within the Central Andean Volcanic Arc of the broader South America Volcanic Regions. Situated at 23.00° S, 67.75° W in the Southern Hemisphere, the volcano lies within a tropical climate zone. At 5,703 meters above sea level, Purico Complex 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 shield, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Purico Complex 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 Purico Complex, 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

The Purico volcanic complex consists of two ignimbrite sheets, separated by a short erosional interval, that were erupted about 1.3 million years ago, along with several stratovolcanoes and lava domes that define a postulated 10 x 20 km ring fracture. Cerro Toco volcano overlies the vent area of the Cajón Ignimbrite. A sulfur mine on its SE flank was mined until the early 1990s. The youngest lava domes, Cerro Chascón de Purico and Cerro Aspero are of Holocene age (de Silva and Francis, 1991). Both domes differ morphologically from many other flat-topped silicic Andean volcanic domes and have conical profiles. The Cerro Chascón de Purico dacitic dome was formed by a series of viscous lava flows and has a well-preserved summit crater and lava flows that show no evidence of glacial modification. The Cerro Aspero appears to be a single Pelean-type dome. The dacitic-to-andesitic Macon stratovolcano of Holocene age lies at the southern end of the complex, and the Alitar maar at the SE end displays constant solfataric activity.

— Smithsonian Institution, Global Volcanism Program