Report on Bezymianny (Russia) — 14 January-20 January 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 January-20 January 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Bezymianny (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 14 January-20 January 2004. Smithsonian Institution and US Geological Survey.
55.972°N, 160.595°E; summit elev. 2882 m
All times are local (unless otherwise noted)
Video footage showed a strong explosion at Bezymianny on 14 January at 1053 producing an ash plume that rose to 6-8 km a.s.l. and extended ENE. A large pyroclastic flow probably traveled SSE down the volcano's flank. This abrupt increase in activity at Bezymianny led KVERT to raise the Concern Color Code from Green (the lowest level) to Red (the highest level), but later the same day they reduced it to Orange. By 1134 on 14 January the ash plume extended ~55 km and was at a height around 6 km a.s.l, and by 1421 it extended ~190 km and was at 4-6 km a.s.l. No ash was deposited in the nearby settlement of Ust'-Kamchatsk. On 16 January the Concern Color Code was further reduced to Yellow. On that day a lava dome was growing and viscous lava was probably flowing slowly from it. Precise seismic monitoring at Bezymianny was hampered due to high-level volcanic tremor at nearby Kliuchevskoi volcano. Visual observations at Bezymianny revealed that gas-and-steam plumes rose to ~100 m above the lava dome.
Prior to the 14 January eruption, a weak thermal anomaly has been registered at Bezymianny since an eruption on 26 July 2003. On 9 January one shallow M 2.2 earthquake was recorded at the volcano. During 10-13 January, a 1-2 pixel thermal anomaly was noted at the volcano and during 10-12 January gas-and-steam plumes rose to low levels above the volcano.
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.