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Report on Bezymianny (Russia) — July 2001

Bulletin of the Global Volcanism Network, vol. 26, no. 7 (July 2001)
Managing Editor: Richard Wunderman.

Bezymianny (Russia) Explosive eruption on 7 August sends plume to ~10 km altitude

Please cite this report as:

Global Volcanism Program, 2001. Report on Bezymianny (Russia). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 26:7. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200107-300250.

Volcano Profile |  Complete Bulletin


Bezymianny

Russia

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

All times are local (unless otherwise noted)


Weak fumarolic activity and gas-steam plumes, along with several small earthquakes, occurred from the latter months of the year 2000 through July 2001. AVHRR satellite data confirmed a one-pixel thermal anomaly on 20 November at 0650, and a weak thermal anomaly on 3 January.

On 23-24 July, seismic and satellite data showed gas-and-steam plumes, along with shallow earthquakes and long local seismic events that were possibly due to collapses and/or avalanches. With the beginning of an extrusive process at the dome, the level of concern was raised from Green (volcano is dormant; normal seismicity and fumarolic activity) to Orange (volcano is in eruption or eruption may occur at any time). KVERT reported that an AVHRR image at 0718 on 26 July revealed a 3-pixel thermal anomaly that had a maximum band-3 temperature of 26.8°C within a background near 8°C. The anomaly had a linear shape and SE-trend from the summit. Afterward, a weakening of activity occurred and the level of concern was lowered to Yellow (volcano is restless; eruption may occur). Intermittent weak activity, including shallow earthquakes, fumarolic activity above the dome, and long local seismic events were observed through 31 July. Weak shallow earthquakes within the volcano's edifice, along with probable collapses and avalanches were recorded during 6-9 August.

On 7 August at 1128 (6 August at 2228 UTC) an explosive eruption began. The level of concern was raised to Red (significant eruption is occurring or explosive eruption expected at any time). Spasmodic volcanic tremor up to 11.7 x 10-6 m/s was recorded until 1300. Tremor amplitude increased up to 1.0 x 10-6 m/s until 1410, then decreased. Observers in Klyuchi town reported that an ash plume 5 km above the volcano rose to 10 km by 1215, and extended to the E-SE. At the same time observers at Kozirevsk village reported that an ash plume rose 2-2.5 km above the dome and extended to the SW. At 1300 a gas-ash plume rose 2 km above the dome and extended SW 40 km. Observers at Kronoki seismic station reported an ash fall (50 g per square m). Satellite images showed a plume centered off the E coast of Kamchatka about 200 km south of Kronotsky. The plume was approximately 200 km long and 100 km wide and headed due S. A thermal anomaly showed that a viscous lava flow had formed at the dome of volcano. After the 7 August eruption through 31 August, background seismicity was recorded and occasional gas-and-steam clouds were observed. The level of concern was dropped to Green.

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.

Information Contacts: Olga Chubarova, Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanic Geology and Geochemistry, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia; Tom Miller, Alaska Volcano Observatory (AVO), a cooperative program of (a)U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), b) Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and c) Alaska Division of Geological & Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA; Tokyo VAAC, Tokyo, Japan (URL: https://ds.data.jma.go.jp/svd/vaac/data/).