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Chile: increased activity at Planchón-Peteroa 8 September 2010

Posted by admin in activity reports, Chile, eruptions, Planchón-Peteroa.
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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

Comments

1. Guillermo - 9 September 2010

The same correction I made to Erik: the earthquake was in February, not January.

2. admin - 9 September 2010

Thanks Guillermo – I’ve put that right. The earthquake was of course on 27 February 2010.


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