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Planchón-Peteroa activity: a new bulletin from SERNAGEOMIN 8 September 2010

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Planchón-Peteroa: aerial view towards the east, showing the arrangement of the craters, the currently active south-western crater and deposits of ash on the icecap and snow. SERNAGEOMIN image, taken on 7 September 2010.

The Chilean state geological service SERNAGEOMIN has issued a new bulletin today on the activity at Planchón-Peteroa, reporting the outcome of an overflight of the volcanic complex which took place yesterday:

On the basis of the overflight of the area of the Planchón-Peteroa volcanic complex carried out on 7 September by SERNAGEOMIN personnel it can be concluded that Planchón volcano is maintaining eruptive activity with weak explosions, possibly of phreatomagmatic origin, similar to minor phases of the eruption recorded in 1991.

The currently active crater is the south-western, which has for several years usually shown persistent fumarolic activity.

The current eruptive activity shows local accumulations of ash in the area within 10 km of the volcano and no alterations have been observed in the glaciers of the volcanic complex.

The activity is described as consisting of ‘discrete pulses of gases and fine ash with a frequency of between 40 and 60 seconds’. These emissions create a ‘weak eruptive column of grey colour’ rising up to 200 metres above the crater, which then disperses towards Argentine territory, to the east of the volcano. The current activity at Planchón-Peteroa, according to SERNAGEOMIN, does not present a hazard to the local population, but continuous monitoring of the volcano will be carried out for as long as the activity continues. Planchón-Peteroa is currently at ‘alert level 4 Yellow’.


Planchón-Peteroa: aerial view towards the south-east, showing the western flank of the Planchón (north)-Peteroa (south) volcanic complex, with prominent ash deposits on the icecap and snow. SERNAGEOMIN image, taken on 7 September 2010.


Planchón-Peteroa: aerial view towards the east, showing the low altitude of the eruption column and the plume dispersing towards the east-south-east, over Argentine territory. SERNAGEOMIN image, taken on 7 September 2010.

Information
Global Volcanism Program: Planchón-Peteroa – summary information for Planchón-Peteroa (1507-04=)

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Chile: increased activity at Planchón-Peteroa 8 September 2010

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Planchón-Peteroa volcano is in central Chile, on the Chile-Argentina border. The complex history of this stratovolcano has produced the present-day nested group of three volcanoes: Azufre, Planchón and Peteroa. All historical eruptive activity has originated from Peteroa – there have been several explosive eruptions of VEI=1 and VEI=2 since the 1870s. Recent fumarolic activity in 2006, 2008 and 2010 underlines that this is very much a restless active volcano.

Reports from Chile indicate that Planchón-Peteroa’s activity is currently increasing and becoming more explosive; on 4 September an Argentine Air Force flight apparently encountered ‘a column of gas and ashes’ reaching up to two kilometres altitude, and the Air Force has also said that an area of 120 square kilometres around the volcano is being affected by ashfall. The Chilean state geological service SERNAGEOMIN issued a bulletin yesterday reporting a change in the activity of Planchón-Peteroa, from its habitual fumarolic venting to ‘eruptive activity’, albeit ‘minor up to now’:

Currently and from a technical point of view, the volcano is changing to moderately explosive eruptive activity, with a phreatic-vulcanian component (solid material) in the acid lakes of the crater zone.

Occasionally during 6 September an eruption column of pyroclasts and gases was observed, black in colour, which reached up to 1,200 metres above the crater zone, with a dispersal plume reaching at least 30 kilometres in length, mostly towards the east and, in a small percentage, to the north and south.

The bulletin notes that a ‘rock-fracturing’ earthquake of magnitude 5.2 at a depth of 13.4 kilometres was recorded on 6 September some 9 kilometres south-east of the volcanic complex. SERNAGEOMIN will be installing a seismological network and working with other Chilean agencies to maintain a full programme of monitoring at Planchón-Peteroa.

There have been suggestions that the current activity may have been sparked by the February 2010 Chilean earthquake (Erik has more on this at Eruptions), which is not the first time an earthquake has been put forward as a possible cause of eruptive activity at Planchón-Peteroa: Watt, Pyle and Mather (2009) suggest (in their Table 2) that an eruption of this volcano in July 1960 may have been triggered by the earthquake of May 1960. Watt et al argue that the incidence of volcanic eruptions in the aftermath of large earthquakes is signficant enough to justify the conclusion ‘that seismic eruption triggering following large earthquakes, with delays of several months, is a significant process in volcanic arcs’ without it being possible to pin down individual eruptions as being the result of particular earthquakes, and certainly it is not possible to say that the 2010 earthquake is responsible for the current activity at Planchón-Peteroa, any more than the same could be said for 1960. There is just not enough evidence to make a solid connection, and anyone who jumps right in with a declaration that big earthquakes = more volcanic eruptions is going way too far, but it’s an important and very interesting line of research; given the complex tectonic context of Planchón-Peteroa there is clearly much more work to be done before a clear conclusion can be reached.

[Thanks to Guillermo for pointing me to Planchón.]

References
José Cembrano & Luis Lara, ‘The link between volcanism and tectonics in the southern volcanic zone of the Chilean Andes: a review’, Tectonophysics, vol. 471, issues 1-2 (9 June 2009), pp. 96-113. [doi:10.1016/j.tecto.2009.02.038]
Daniel R. Tormey, Frederick A. Frey & Leopoldo Lopez-Escobar, ‘Geochemistry of the Active Azufre—Planchon—Peteroa Volcanic Complex, Chile (35°15′S): Evidence for Multiple Sources and Processes in a Cordilleran Arc Magmatic System’, Journal of Petrology, vol. 36, no. 2 (April 1995), pp. 265-298. [doi: 10.1093/petrology/36.2.265]
Sebastian F. L. Watt, David M. Pyle & Tamsin A. Mather, ‘The influence of great earthquakes on volcanic eruption rate along the Chilean subduction zone’, Earth and Planetary Science Letters, vol. 277, issues 3-4 (30 January 2009), pp. 399-407. [doi:10.1016/j.epsl.2008.11.005]

News
Entró en actividad el volcán Peteroa, en la frontera entre Mendoza y ChileLa Capital, 6 September 2010
Preocupa actividad de volcán PeteroaLa Estrella de Concepcion, 6 September 2010
Región del Maule: Sernageomin detecta actividad irregular en volcán Planchón y monitorea el Peteroa – Radio Bío-Bío, 7 September 2010
Planchon volcano starts spewing rocks, gases, Chile’s geology service says – Bloomberg, 7 September 2010
Volcán Planchón entró en actividad eruptiva en la Región del MauleEl Mercurio, 8 September 2010

Information
Global Volcanism Program: Planchón-Peteroa – summary information for Planchón-Peteroa (1507-04=)

The Volcanism Blog

Chaitén town ‘90% flooded’ – ONEMI 15 May 2008

Posted by admin in activity reports, Chaitén, Chile, eruptions, natural hazards, Planchón-Peteroa.
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According to the Chilean Oficina Nacional de Emergencia (bulletin, 14 May 2008) the town of Chaitén is currently severely flooded because of a combination of the overflowing of the Chaitén river and the recent rains: ‘According to reports from an overflight of the Chaitén area conducted by the Air Force, the town is 90% flooded due to increased flows of the Río Blanco or Río Chaitén and the occurrence of precipitation’. The river was reported on 13 May to be choked with volcanic ash and pumice, causing flooding.

Terra España today has a full report on the situation at Chaitén:

The suffering city, stricken by the tragedy of the violent eruption of the volcano which forced the evacuation of its more than 4,000 people on 2 May, now faces relentless rain. According to reports from the area, the accumulation of water ranges from 50 centimeters to one meter, and in some cases is mixed with mud of the sediments which the volcano has deposited in the Río Blanco and Río Rayas.

The Chilean Government has ordered that the 50-kilometre exclusion zone around the town of Chaitén will remain in place for the next three months because of the dangerous conditions in and around the town: ‘Many of the evacuated families asked the government for permission to return home to collect their belongings, but this was not permitted because of the deteriorating situation’.

Meanwhile fumarolic activity at the volcano Peteroa, situated on the Chile-Argentina border some 800 kilometres north of Chaitén, has provoked concern among the authorities, who are clearly determined not to be taken by surprise again. ONEMI notes today that the reports of increased activity may be due to changed atmospheric conditions making the fumaroles more visible, rather than any actual alteration in the volcano’s behaviour. The regional ONEMI director will be visiting the area to assess the situation tomorrow.

For all our Chaitén coverage: Chaitén << The Volcanism Blog

Information
Global Volcanism Program: Chaitén – summary information for Chaitén (1508-41)
Global Volcanism Program: Planchón-Peteroa – summary information for Planchón-Peteroa (1507-04=)
ONEMI, Oficina Nacional de Emergencia – Chilean government emergencies office (Spanish)
SERNAGEOMIN – volcanology information from the Servicio Nacional de Geología y Minería, Chile (Spanish)

News
Nuevo aluvión deja a casi todo Chaitén bajo el agua – 123 Chile, 15 May 2008 (Spanish)
Un 90% de Chaitén está bajo el agua por las fuertes lluvias y el desborde de ríos – Terra España, 15 May 2008 (Spanish)
Ponen candado pueblo chileno por volcán e inundación – Reuters América Latina, 15 May 2008 (Spanish)

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