Cause
Effect
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 and Auckland, 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 atomic bombs.
Prediction
On Saturday, a volcano in the Puyehue-Cordon Caulle chain of south-central Chile erupted after lying dormant for more than 50 years. The government evacuated several thousand residents as Puyehue threw ash more than 6 miles (10 km) into the sky, pushing the plume toward neighboring Argentina. Authorities had already put the area around the volcano on alert after a flurry of earthquakes earlier on Saturday -- at one point, the tremors reached an average of 230 per hour.
Cordón Caulle is a major area of geothermal activity,[6] as manifested by the several hot springs, boiling springs, solfataras and fumaroles that develop on it. The geothermal system in Cordón Caulle consists of a vapour dominated system overlain by a more superficial steam heated aquifer.[7] The temperatures of the vapour systems range from 260–340 °C and 150–180 °C for the aquifer.[8] The uppermost part of the geothermal system, at 1500–2000 m (4,921–6,562 ft), is characterized by fumaroles and acid-sulfate springs.[7] Cordón Caulle is considered one of the main sites of geothermal exploration in Chile. Chile's main areas of geothermal activity are located in the Andes of the Far North and in the south-central areas of the country. Geothermal systems in Chile are associated with volcanoes
Mitigation
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Citing a "real tragedy" in Argentina caused by the volcano, Kirchner said the government would double social benefits, as well as defer tax payments and obligations for the hardest-hit Andean cities and towns, including the skiing resort city of Bariloche and Villa La Angostura in the Andean mountains.
The Patagonia mountain range in southwestern Argentina, home to both cities, was declared an environmental disaster area after a massive layer of volcanic ash was dumped there following an eruption.
In a speech broadcast on national television, Kirchner said $2.41 billion dollars would also be awarded to 1,400 farmers and businesses in the affect area on the condition that they don't fire their workers.
The president said another $7 million will be allocated to pay for cleanup operations, while a road will be built in Bariloche to provide work for locals.
The government also hopes that flights will return to normal to and from the affected areas starting Wednesday, giving a break to a region heavily dependent on tourism two weeks after the onset of the winter ski season in Argentina.
Airports in Bariloche and Neuquen have remained closed since June 4 when the volcano erupted in southern Chile and winds spread the ash across much of southern Argentina, intermittently grounding commercial flights and airports in and around Argentina's capital.
Livestock and agriculture in the provinces of Rio Negro and Neuquen were also affected, and declared an emergency due to the economic damage.
Flights from airports across South America -- including hubs in Montevideo, the Chilean capital Santiago and southern Brazilian cities -- have also been hit in recent weeks due to ash clouds, which swept around the Southern Hemisphere to linger over Australia and New Zealand.
The Puyehue, which rumbled to life early this month for the first time since 1960, is high in the Andes mountains, 870 kilometers (540 miles) south of Santiago and near the border with Argentina.
Response
The Chilean airline LAN cancelled flights to Temuco and Valdivia in the south of the country, and a number of flights were suspended in Australia and New Zealand.
Evacuation A "red alert" was declared pre-emptively by the National Emergencies' Office (ONEMI) for regions near the volcano: Puyehue, Río Bueno, Futrono, and Lago Ranco; initially 600 persons were evacuated. The "red alert" was later extended for the Los Ríos Region area: the areas of Pocura, Pichico, Los Venados, Contrafuerte, El Zapallo, Futangue, Pitreño, Trahuico, Riñinahue Alto, Ranquil, Chanco, Epulafquén, Las Quemas, Licán, Boqueal, Rucatayo, and Mantilhue were evacuated; and areas in the Los Lagos Region such as El Retiro, Anticura, El Caulle, Forestal Comaco, and Anticura Pajaritos were also evacuated, increasing the number to at least 3,000 total evacuated people.[13] It was reported that, at first, large land- and farm-owners in Chilean rural areas near the volcano did not allow workers to be evacuated.[14] According to Chilean authorities, the evacuated persons "would be relocated in temporary shelters in safe areas." There are no reports of deaths or injuries. The families who refused to be evacuated from the riverbed of Rio Nilahue were removed by force by the Carabineros de Chile after a resolution of the Appeal Court of Valdivia. It took the police more than 8 hours to evacuate 40 people. People resisted mainly because they had to leave their livestock behind.[15] Small livestock farmers were permitted to check and care for their livestock once a day.[16] On 17 June 2011 OVDAS reported that the ash-and-gas plume reached 3 kilometres (1.9 mi) above sea level, and the frequency of earthquakes had dropped to 5 per hour. They reduced the alert level from 6 (moderate eruption) to 5 (imminent eruption), and at least 100 evacuated persons were allowed to return home.[17][18] People from the Northeast side of the Cordón (Nilahue and Gol Gol Valley) will stay in the shelters. On 19 June the ONEMI decided that all 4,200 evacuees could return home, as the scale of the eruption continued to decrease.[19]