Kamchatka Volcanic Eruptions Response Team (KVERT) reports, through the Alaska Volcano Observatory (AVO), indicate that a weak thermal anomaly registered on satellite images following the 26 July 2003 eruption and continuing until an eruption on 14 January 2004.

January 2004 eruption. A shallow earthquake of local magnitude (Ml) 2.2 was reported at Bezymianny on 9 January. The eruption itself began at 1053 on 14 January, sending ash plumes to 6-8 km altitude to the ENE, decreasing to 3.5 km altitude later in the day. KVERT reported that a large pyroclastic flow probably formed on the ESE flank. On 15 January, gas-steam plumes rose to 100 m above the lava dome, increasing to 500 m on 16 January. A 2- to 8-pixel thermal anomaly registered on these days. Satellite images on the morning of 14 January showed ash clouds about 30 km wide extending 150 ENE km, increasing to 250-300 km ENE that afternoon. Meaningful seismic monitoring was thwarted during the eruption period due to high-level volcanic tremor at nearby Kliuchevskoi volcano. The eruption caused the hazard status to temporarily rise to the highest level (red).

KVERT weekly reports for the period from the 14 January eruption to 16 April indicate continuing unrest at Bezymianny. The lava dome was reported to be growing, with no detectable seismicity, gas-steam plumes were rising ~ 3-4 km and dispersing in the wind (generally to the S), and the number of pixels in thermal anomalies reduced from 1-4 early in the period to 1-2 late in the period.

25 December 2002 eruption. A substantial eruption at Bezymianny on 25 December 2002 was not reported in the Bulletin. That eruption followed a 1-pixel thermal anomaly on 23 December that increased to 7-10 pixels on 24-25 December, with seismicity slightly above background levels. Weak intermittent spasmodic tremor occurred on the 25th, when a very hot plume that probably contained ash was visible, and moderate explosive activity began around 1900. Seismic data revealed a large explosive eruption on 26 December at 0715. The resultant ash cloud rose to 5 km altitude. and deposited ash in Kozyrevsk, 55 km NW of Bezymianny. The eruption continued through the 27th, but activity decreased. On 1 January 2003 a weak thermal anomaly was noted over the volcano, probably reflecting a viscous lava flow on the dome.

Geological Summary. The modern Bezymianny, much smaller than its massive neighbors Kamen and Kliuchevskoi on the Kamchatka Peninsula, was formed about 4,700 years ago over a late-Pleistocene lava-dome complex and an edifice built about 11,000-7,000 years ago. Three periods of intensified activity have occurred during the past 3,000 years. The latest period, which was preceded by a 1,000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large open 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 Girina, Kamchatka Volcanic Eruptions Response Team (KVERT), a cooperative program of the Institute of Volcanic Geology and Geochemistry, Far East Division, Russian Academy of Sciences, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia, the Kamchatka Experimental and Methodical Seismological Department (KEMSD), GS RAS (Russia), and the Alaska Volcano Observatory (USA); Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, PO Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.