The 2011–2012 Puyehue-Cordón Caulle eruption () 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.Erupción del Cordón Caulle es similar a la de mayo de 1960 At least 3,500 people were evacuated from nearby areas,Volcán Puyehue: Gobierno evacua a 3.500 personas La Nación, 4 June 2011 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.Reporte Especial No 13 de Actividad Volcánica
Between 20:00 on 2 June and 19:59 on 3 June, OVDAS reportedReporte Especial de Actividad Volcánica No 26 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. The alert level remained at 3, yellow. Area residents reported feeling earthquakes during the evening of 3 June through the morning of 4 June.
On 4 June, at 11:30 local time, a new round of eruption in the Puyehue volcano began. For a six-hour period on 4 June seismic activity increased to an average of 230 earthquakes per hour, at depths of 1–4 km. About 12 events were magnitudes greater than 4 of Richter magnitude, and 50 events were magnitudes greater than 3. The alert level was raised to 5, red.Reporte Especial de Actividad Volcánica No 27
At 15:15 local time OVDAS reported an explosion and a -wide ash-and-gas plume that rose to an altitude of above sea level. The plume drifted south at altitude, and southeast and east at altitude. The alert level was raised to 6, red.Reporte Especial de Actividad Volcánica No 28
18 days after it first erupted, lava begun spilling from the volcano, heading west and flowing "slowly by a channel about 50 meters wide and 100 feet long."Puyehue volcano began to fire lava on 23. June 2011Reporte Especial de Actividad Volcánica No 48
According to Argentine physicists, the eruption sent one hundred million tons of ash, sand and pumice stone, equivalent to the load of 24 million trucks of sand and released power equivalent to 70 Hiroshima atomic bombs (equal to 1000 kilotons of TNT). The eruption, though violent, is expected to fertilize the land and rivers. Evaluation of the total amount of airborne erupted material has proved to be challenging, with estimated values ranging from . A further of lava were erupted in the months following the first explosions.
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.Complejo Puyehue – Cordón Caulle entró en fase eruptiva , ONEMI, 4 June 2011. La responsabilidad de la conducción nacional de la Protección Civil en Chile corresponde al Ministerio del Interior, la que ejerce mediante su servicio especializado: ONEMI, Access date: 4 June 2011 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. 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.Tele 13 on 10 June 2011 Small livestock farmers were permitted to check and care for their livestock once a day.Life in the shelter: evacuees from Volcán Puyehue try to regain normality
On 17 June 2011 OVDAS reported that the ash-and-gas plume reached 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.Article Sernageomin baja nivel de alerta volcánica y al menos 100 evacuados pueden retornar in newspaper "La Tercera" on 17 June 2011, retrieved on 18 June 2011 Article Volcán Puyehue: Algunos evacuados regresarán a sus casas 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.Article in earthquake-report.com on 19 June 2011 retrieved on 19 June 2011
Ash cloud over Argentina and Uruguay
The ash cloud crossed Chile's borders and precipitated over the Argentine cities of Villa la Angostura, Bariloche and the northern part of Chubut province.Evacúan a 3.500 personas por la erupción del volcán Puyehue en Chile , [Infobae.com],04-06-11, access date:4 June 2011.Aumentan a 3500 los evacuados por actividad volcánica en Puyehue-Cordón Caulle The eruption was reported to have produced lightning and strong thunderstorms.La columna de humo del volcán Puyehue alcanza los 10 kilómetros de alto Argentine Minister of Defense Arturo Puricelli ordered that "the Argentine Army personnel, means of transport, water treatment plants, and other equipment of VI Mountain Brigade in the province of Neuquén" be moved to the affected areas on the Argentine border with Chile.
In Argentina's affected cities, people have been recommended to stay indoors.
On 5 June the ash rain in Bariloche ceased. There were reports that the ash had caused power outages and prompted the local airport to be closed. The Bariloche Atomic Centre reported that the ashes contain no crystal phases of quartz or cristobalite.
On 9 June ash clouds from Puyehue reached Uruguay, forcing most flights to be cancelled. On 11 June the ash clouds reached the southern tip of New Zealand, with unusual sunsets reported in Invercargill.
Further disruption was caused by ash in October 2011, with airports at Mendoza, Bariloche and Buenos Aires closed and flights to Buenos Aires and Montevideo cancelled. This was ash from the earlier eruption which had been deposited across Patagonia and stirred up by high winds. Some areas of Argentina close to the Chilean border still had ash falling almost daily four months after the June eruption.
River temperature and contamination The eruption of the Chilean volcano Puyehue significantly affected the surrounding environment. The temperature of the Nilahue River rose to and killed an estimated 4.5 million fish with an economic impact on fish farming in the area. The cattle economy was also damaged.Article Puyehue disrupts air traffic on 10 June 2011, retrieved on 10 June 2011
Scientists from the Southern University of Chile analyzed waters from the Nilahue and Golgol rivers, the two principal collectors of waters from Cordón Caulle. Scientists found that if solid particles were removed the water was safe to drink.Estudio sostiene que ríos del Cordón Caulle no están contaminados y son potables , La Tercera.
Although very little ash was deposited on the western side of the volcano, the ash reached Puyehue Lake through river transport, depositing a layer of tephra at the bottom of the lake.Bertrand et al. (2014) Deposition of the 2011–2012 Cordón Caulle tephra (Chile, 40°S) in lake sediments: Implications for tephrochronology and volcanology, Journal of Geophysical Research – Earth Surface.
Livestock The ash cloud led Argentina to declare a state of emergency for farmers as the prolonged eruption's continued effect on the 2 million head of sheep that graze in southern Argentina. Chubut and Río Negro Provinces had suffered five years of drought, and the ash destroyed the little pastureland still serviceable. 750,000 sheep suffered the consequences, and Rio Negro officials said 60,000 head of cattle also were "at risk."Agriculture emergency is Argentine Patagonia because of the volcanic ash The livestock had suffered major heart attacks and many of which contracted throat cancer, resulting in death.
Whereas there appears to be no published support for the existence of heart attacks or throat cancer as a consequence from the exposure to ashes and causing death, there are at least two phenomena which play a role. First, the physical reduction of available forage (on top of the prevailing general drought conditions) has resulted in lack of forage, and therefore, starvation with all its consequences. This was accelerated by the rapid wear of teeth from the abrasive action of ashes, and thus a reduced efficiency to forage. Second, these ashes cause fluoride intoxication in herbivores, with many different symptoms, and confirmed in sheep, cattle and horses.Flueck WT. 2013. Effects of Fluoride intoxication on teeth of livestock due to a recent volcanic eruption in Patagonia, Argentina. Onl J Vet Res., 17 (4): 167–176.
Wildlife and forests However, besides livestock, also wild species are strongly affected by the ashes. Fluoride intoxication was first discovered in red deer (Cervus elaphus), with pronounced dental fluorosis. The result is formation of abnormal teeth both in physical form as well as in reduced hardness. It reduces foraging efficiency, eliminated pregnancies in subadults, and will reduce longevity by 50–75%. While the rate of fluoride intake exceeds the capacity to eliminate it, animals continue to accumulate fluoride. Before the eruption, fluoride levels in adults was about 50–60 ppm. On average, deer were judged to accumulate about 1,000 ppm per year under similar exposure to ashes, which remains the situation for many drier sites, where the winds constantly redeposit the ashes. Some deer accumulated more like 3,700 ppm per year and reached 5,175 ppm by the year 2012. This trend has remained for some areas as the most recent deer examined had adults which had reached 10,396 ppm. These high levels of fluorosis likely affect the skeleton, and a first case in deer with severe osteological pathology has been described in March 2015.
A study along Chile Route 215 showed that in places with ash falls of 10 cm about 8% of the trees died while at locations with 50 cm of ash 54% of the trees died. Ashes did not cause any significant abrasion of the canopy.