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Report on Bezymianny (Russia) — 29 August-4 September 2012

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 29 August-4 September 2012
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2012. Report on Bezymianny (Russia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 August-4 September 2012. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (29 August-4 September 2012)


Bezymianny

Russia

55.972°N, 160.595°E; summit elev. 2882 m

All times are local (unless otherwise noted)


KVERT reported that seismic activity at Bezymianny had increased in the middle of August. During 24-31 August levels were moderate; 17 events were recorded on 28 August and 71 events were recorded on 31 August. Observers noted weak-to-moderate fumarolic activity during 25-26 and 29 August; cloud cover prevented observations on the other days. A thermal anomaly was detected in satellite imagery on 25 August.

Based on seismic data analyses, an explosive eruption occurred from 0716 to 0745 on 2 September. Ash plumes rose to altitudes of 10-12 km (32,800-39,400 ft) a.s.l. and drifted more than 1,500 km ENE. A thermal anomaly observed in satellite imagery was very bright before the explosion. The Aviation Color Code was raised to Orange, then Red. Ash plumes rose to an altitude of 4 km (13,100 ft) a.s.l. and drifted NE later that day, then ash emissions ceased. Ash plumes continued to be detected in satellite imagery and drifted 450-600 km ENE and SE. The Aviation Color Code was lowered to Yellow. On 3 September seismic activity was low. A viscous lava flow effused on the lava-dome flank, and was accompanied by fumarolic activity and hot avalanches.

Geologic Background. Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)