2011–2012 Puyehue-Cordón Caulle eruption

The 2011–2012 Puyehue-Cordón Caulle eruption ([puˈʝewe]) was a volcanic eruption that began in the Puyehue-Cordón Caulle volcanic complex in Chile on 4 June 2011. The eruption, which occurred from the Cordón Caulle fissure after 51 years of the volcano being inactive, is one of the largest volcanic eruptions of the 21st century thus far. At least 3,500 people were evacuated from nearby areas, while the ash cloud was blown across cities all around the Southern Hemisphere, including Bariloche, Buenos Aires, Montevideo, Stanley, Porto Alegre, Cape Town, Hobart, Perth, Adelaide, Sydney, Melbourne, Wellington, Auckland and Port Moresby, forcing airlines to cancel hundreds of international and domestic flights and causing travel chaos.

By 18 June the ash cloud had completed its first circle of the globe. The Chilean civil aviation authority said that "the tip of the cloud that has travelled around the world has more or less reached the town of Coyhaique", about 600 kilometres south of the Puyehue-Cordón Caulle.

An estimated one hundred million tons of ash, sand and pumice were ejected – requiring power equivalent to 70 Hiroshima atomic bombs.

Cordón Caulle is a volcanic fissure and has erupted many times in recorded history, most recently in 1960, following the 1960 Valdivia earthquake days earlier, whereas the Puyehue stratocone has remained dormant.

Eruption

The Southern Andean Volcano Observatory (OVDAS) of Servicio Nacional de Geología y Minería de Chile (SERNAGEOMIN) reported on 27 April 2011, 15:30 local time, an increased seismicity at the Puyehue-Cordón Caulle and set the alert Level to 3, Yellow.

Between 20:00 on 2 June and 19:59 on 3 June, OVDAS reported that about 1,450 earthquakes at Puyehue-Cordón Caulle were detected, or an average of about 60 earthquakes per hour. Scientists and regional authorities flew over the volcano, noting no significant changes.