Copahue (Spanish pronunciation:[koˈpawe]) is a stratovolcano in the Andes on the border of Bío Bío Region, Chile and Neuquén Province, Argentina. There are nine volcanic craters along a 2 km (1.2 mi) line, the easternmost of which is historically the most active, and contains a 300 m (1000 ft) wide crater lake with a pH ranging between 0.18 and 0.30.[2] Eruptions from this crater lake have ejected pyroclastic rocks and chilled liquid sulfur fragments.[1] Although the lake emptied during the 2000 eruption, it later returned to its previous levels. Copahue means "sulphur waters" in Mapuche.[3]
Copahue sits on a basement of sedimentary and volcanic rocks ranging in age from Eocene to Pliocene.[2] The modern volcano sits in a volcanically active area, with a caldera from the Pliocene, measuring 20 km by 15 km, lying to the east of Copahue. The modern volcano became active roughly 1.2 million years ago (Ma).[2] The modern caldera formed 0.6 to 0.4 Ma, and produced large pyroclastic flows, extending up to 37 km from the volcano.[2]
Satellite image of the December 2012 eruption
The modern structure is an elongated shield volcano, with a maximum thickness of 22 km and a minimum of 8 km.[2] It has erupted ten times since 1900, most recently in March 2016.[1][3][4] On 27 May 2013, it was reported that a red alert had been issued and the evacuation of around 2,000 people was to begin.[5]
González-Ferrán, Oscar (1995). Volcanes de Chile. Santiago, Chile: Instituto Geográfico Militar. ISBN956-202-054-1. (in Spanish; also includes volcanoes of Argentina, Bolivia, and Peru)
