A major eruption of Calbuco, a volcano in southern Chile, has melted glacier ice, creating large flood events.
The eruption on 22 April came as a near-total surprise, since it had been preceded by only two hours of increased seismic activity, according to Chile’s National Service of Geology and Mines. It shot incandescent masses of lava to a distance of over 5 kilometers. Its ash plume reached about 15 miles high, and layers of ash 40 centimeters thick have been deposited over a large area in Chile, Argentina and Uruguay, threatening to contaminate water supplies and cause roofs to collapse. Government agencies in Chile placed the region on red alert, the highest warning level, and evacuated over 4000 people from Ensenada and other small towns within 20 kilometers of the volcano. The evacuated people were taken by bus to nearby cities. Officials in Puerto Montt and other cities declared curfews to prevent looting in homes and businesses. Airplane flights in the region were cancelled because of the threat of damage to the planes from ash and from the greatly reduced visibility. A second eruption took place the next day, with an ash cloud of similar height.
There have been contradictory reports about lava flows. Initial accounts mentioning a flow into a lake high on the mountain have not been confirmed, and they may have just described pyroclastic flows—masses of hot gas and rock. Local sources state that pyroclastic flows have melted glacial ice, causing flooding in the Rio Blanco which has washed away bridges, damaged roads, and trapped individuals who cannot cross the high waters.
— El Dínamo (@el_dinamo) April 23, 2015
The scale of the eruption can be seen in this video:
Calbuco has erupted at least 10 times in the last 200 years, with several eruptions larger than the ones in the last two days. Though the volcano seems quiet at present, it may erupt again in the near future. Villarrica, another glacier-covered volcano in Chile about 290 kilometers to the north-northeast of Calbuco, had erupted earlier this year, but also remains quiet for the moment. As of the time of writing, however, the ash cloud, seen below, continues to cause damage over a large area of Chile and Argentina.