Smithsonian Institution
Global Volcanism Network Bulletin v. 20, no. 9, September 1995

Bezymianny (Kamchatka Peninsula)  Explosive eruption causes 2-3 mm
       of ashfall 50 km away

Bezymianny
Kamchatka Peninsula, Russia
55.98N, 160.59E; summit elev. 2,882 m
All times are local (= GMT + 12 hours)

At 0500 on 6 October, regional seismic stations began to record
volcanic tremor with a maximum amplitude of 5-6 fm. An ash plume
was detected by the Alaska Volcano Observatory (AVO) on a satellite
image taken at 0824. The Institute of Volcanology (IV) reported
that an eruptive column first appeared over Bezymianny around that
time, and by 0900 it was ~8 km high. Weather satellite imagery at
0948 showed that the plume had reached the coastline nearly due E,
with a top estimated to be 10 km  above sea level.

At 0930, volcanic ash started to fall in Kliuchi, ~50 km NNE.
Tremor and ash emission increased up to 1200, followed by 3 hours
of intense ashfall; during a period of 140 minutes 700 g/m^2 of ash
fell in Kliuchi. Because the air in Kliuchi was strongly polluted
with volcanic gas, a warning was issued for the residents to take
precautions. From Kliuchi, E. Zhdanova, a volcanologist from the
Institute of Volcanic Geology and Geochemistry (IVGG), reported
that ashfall had stopped at about 1700 on 6 October after 2-3 mm of
deposition. AVO satellite imagery at 1813 showed the disconnected
ash plume ~150 km E. The plume was moving ENE and was over 400 km
from the source. By about 0930 on 7 October, the ash plume had
undergone significant diffusion and was no longer detectable on
satellite images.

As of the morning of 7 October the volcano was obscured, but there
was no more tremor. Zhdanova suggested that the explosive phase of
the eruption had ended and a lava dome was forming again. This
interpretation was confirmed by a large hot spot seen at the vent
on AVHRR imagery after the ash cloud had disconnected from the
volcano.

An eruption in 1955-56 ended ~1,000 years of quiescence and formed
a large horseshoe-shaped caldera. During the past few years, lava
has extruded in the summit area and occasional dome collapses have
produced pyroclastic flows. Explosive activity that began in
October 1993 (Bulletin v. 18, nos. 9-11) ejected ash that fell in
Kliuchi. A large plume with a small amount of ash was observed in
early 1994 (Bulletin v. 19, no. 1). Small steam plumes were last
reported in October and November 1994 (Bulletin v. 19, no. 12).

Information Contacts: Alaska Volcano Observatory (AVO), a
cooperative program of (a) U.S. Geological Survey, 4200 University
Drive, Anchorage, AK  99508-4667 USA (Email:
tkeith@tardaddy.wr.usgs.gov), (b) Geophysical Institute, Univ. of
Alaska, P.O. Box 757320, Fairbanks, AK 99775-7320 USA (Email:
eich@dino.gi.alaska.edu), and (c) Alaska Division of Geological &
Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK
99709 USA; E. Zhdanova and V. Kirianov, Institute of Volcanic
Geology & Geochemistry, Piip Avenue 9, Petropavlovsk-Kamchatsky
683006, Russia; N.A. Zharinov and S.A. Fedotov, Institute of
Volcanology, Petropavlovsk-Kamchatsky 683006, Russia.