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Earth of fire

Actualité volcanique, Article de fond sur étude de volcan, tectonique, récits et photos de voyage

A recent article in Live Science , titled " Volcanic eruption Creates deadly acid lake" leads us to look again at the eruption of the volcano Karymsky in 1996 .

karymsky volcano - Mikhail ZelenskyThe Karymsky and Akademia Nauk ( Lake Karymsky ) on the right - Photo Mikhail Zelensky / Live Science

Located in the Kamchatka Peninsula , the Karymsky known between 1970 and 1982 an active period, followed by 13 years of dormancy. After five months of growth, the seismic activity culminates in a volcano- tectonic 6.9 magnitude earthquake on 1 January 1996 , followed by a dozen aftershocks of magnitude 5 or greater .

Simultaneous eruptions of Karymsky and Akademia Nauk :

On 2 January 96 around midnight , one day after the earthquake, a first eruption marks the Karymsky , it expels ash and lava from a new summit crater, located southwest of Crater 70-82 , until an altitude of 7,000 meters. The ash cloud will spread over 200 km. S / SE of the volcano.

1996.01.02 Karymsky
           Karymsky erupting on 02.01.1996 - Courtesy of the Institute of Volcanology / GVP .

In the afternoon , a second eruption occurs at a new eruptive center , located in the Akademia Nauk caldera, occupied by Karymsky lake. This hydroclastic eruption ejected, in pulse, columns of ash and steam, every 5 to 6 minutes for 18 hours ... in front of scientists from the Institute of Volcanology and Seismology Kamchatka .

1996.01.02 - GVP2105kar3
02.01.1996 - Simultaneous eruptions of Karymsky (right) and Akademia Nauk (left) - the vents are 6 km apart . Courtesy of the Institute of Volcanology / GVP .

1996.01.02 Karymsky - GVP
Akademia Nauk - one of the largest sub- lacustrine eruptions - the base of the cloud in formation measures 1,000 meters wide - Courtesy of the Institute of Volcanology / GVP .

Twelve hours only between these two eruptions , which is thus considered as simultaneous in geologic time scale .

However, they have
quite different characteristics : the eruption of Karaymsky produced andesites , while the Akademia Nauk gives products basaltic to rhyolitic in nature.
The hypothesis has been advanced of the penetration of the crustal portion of the magmatic system Karymsky by a basaltic dyke , in connection with an extension of 2.3 meters amplitude perpendicular to the fault connecting the two vents, action that triggered the release of andesitic magma from a tank at a higher level .

Karimsky - map aeic.alaska.edu
Karymsky and Akademia Nauk - map of recent pyroclastic deposits - Fault : red line - extension area , marking the intrusion of a dyke, in orange. - Aeic.alaska.edu map

At the lake, a large part of the ejected material (30-40 million tonnes) falls into one, forming there a mix of sodium, calcium and magnesium sulphate salts , yellowish-brown color, and an acid pH 3.2 .

But the eruption under the Lake , described by VEI 3 GVP, boil and evaporate the shallow lake water, causing tsunamis, with waves over 20 meters that pounded the shore at each new explosion and ripped the trees.
All animal life was literally cooked, then shredded by the tsunamis.
A small crater was formed on the north shore of the lake, and new hot springs appeared ... this landscape of Apocalypse was covered with a layer of mud. The Karymsky River, which drains the lake, is no longer visible , buried under the ashes ... only many fumaroles mark its source .

P1100829 - CHB
        Helicopter excursion over Karymsky and its lake in 2010 - Photo Carole and Frederic Hardy

An expedition in 2002 confirms the restoration of pH 7.54 , the waters have again become clear, but still three times saltier than before the eruption ... hot news sources provide more minerals in the lake , increasing the salinity. If the look is restored, the Karymsky lake has not yet returned to its original state .

Meanwhile, the effusive activity and / or andesitic vulcanian-strombolian - type of the Karymsky continues its path .



Sources :

-Live Science - Stranger than fiction : Volcanic eruption creates deadly acid lake - link

- Global Volcanism Program - Karymsky

- Global Volcanism Program - Akademia Nauk

- Eichelberger John C. and Izbekov Pavel E. (2000) : Eruption of andesite triggered by dyke injection : contrasting cases at Karymsky Volcano, Kamchatka and Mt Katmai, Alaska. Phi/ Trans. R. Soc. Lond. A 358, pp. 1465-1485.  

- Fazlullin S.M, Ushakov R.A, Shuvalov A., Aoki M., Nikolaeva A.G and Lupikina E.G. (2000) : The 1996 subaqueous eruption at Academii Nauk volcano (Kamchatka) and its effects on Karymsky lake. Journal of Volcanology and Geothermal Research, vol. 97, pp. 181-193.

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