Friday, 9 November 2012

Eruption on Mount Kizimen.

Kizimen is a stratovolcano (cone-shaped volcano) with a summit made up of lava-domes and blocky flows, which has been compared to Mount St Helens in Washington State, USA, before its catastrophic 1980 eruption. It is located on the southeast of the Kamchatka Peninsula, and rises 2376 m above sea level. Prior to 1910 only one eruption had ever been recorded on Mount Kizimen, in 1927, and the volcano had been assumed to be inert. However since then the level of activity on Kizimen has grown steadily, leading to concerns that it may be heading for a St Helens style catastrophic eruption. The volcano appears to have done this several times in the past, with geology suggesting that previous periods of dome-building have been followed by major explosions around 10 000, 8400 and 1100 years ago.

Map showing the position of Mount Kizimen on the Kamchatka Peninsula. Google Maps.

Between 26 October and 2 November 2012 the Kamchatka Volcanic Eruption Response Team reported a rise in seismic activity (Earthquakes) around Mount Kizimen. This was followed by satellite observations of a thermal anomaly on the volcano (i.e. an infra-red camera on a satellite detected heat on the volcano, but since this was not a visual siting it was not possible to tell if this was within the volcano or lava at the surface). Further satellite and ground observations includes glowing from the crater, lava flows on the east flank of the volcano, gas and steam emissions and avalanches of hot ash on the southern flank. On 2 November the Tokyo Volcanic Ash Advisory Center issued a warning that the volcano had produced an ash column rising 5.2 km above the summit, which drifted to the northeast. Further ash columns were seen from 2 to 5 November, and incandescence from the crater and lava flows were again seen on 5 November.

Image from NASA’s Terra Satellite taken on 1 November 2012, showing a column issuing from Kizimen (bottom right). NASA/Earth Observatory.

The Kamchatka Peninsula lies on the eastern edge of the Okhotsk Plate, close to its margin with the Pacific and North American Plates. The Pacific Plate is being subducted along the margin, and as it does so it passes under the southern part of the Kamchatka Peninsula, and as it does so is partially melted by the friction and the heat of the Earth's interior. Some of the melted material then rises through the overlying Okhotsk Plate as magma and fueling the volcanoes of southern Kamchatka.

Map showing the movement of the Pacific Plate relative to the Kamchatka Peninsula. Saha et al. (2012).


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