Small phreatic(?) eruption on 30 June and continued fumarolic activity

Fumarolic activity continued from June through mid-October 2000. Volcanic tremor was slightly above background levels until it increased markedly at 1800 on 26 June. At 0751 on 30 June, seismicity indicated a short-lived vigorous phreatic(?) eruption. By 4 July, volcanic tremor decreased to background levels. Weak fumarolic activity continued to be observed, and on 22 July, a fumarolic plume rose 200-300 m above the volcano. On the same day, two small volcano-tectonic earthquakes occurred between Mutnovsky and neighboring Gorely volcano. Near noon on 31 July, a fumarolic plume rose 500 m above the summit.

A single volcano-tectonic earthquake occurred under the volcano on 9 August. A gas-and-steam plume rose to a height of 200-300 m and drifted 5 km E. On 30-31 August, a gas-and-steam plume rose 100-500 m above the volcano and moved 1 km NW. Fumarolic plumes rose 200-500 m above the summit on 1 and 7 September. Occasional fumarolic activity continued throughout September with plumes reaching up to 300 m above the volcano. On 8 October, gas-and-steam explosions rose 800-1,000 m above Mutnovsky and drifted NW. The following day, similar explosions rose 300-600 m and the plume extended 2 km E.

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.

Information is preliminary and subject to change. All times are local (unless otherwise noted)

August 1993 (BGVN 18:08) Cite this Report

Rock avalanches observed within summit crater

During fieldwork on 17-18 September, two geologists from the IVGG noted large rock avalanches within the summit crater at intervals of several hours and intense melting of the glacier inside the crater. The observations indicate that activity inside the crater has increased compared to last year. The next day, a large rockslide (hundreds of thousands of tons of material) buried ~300 m of a trail in the crater under big blocks up to several meters high. Explosions from a vent in the central part of the crater ejected boiling mud several meters high. IVGG is advising hikers and other visitors to stay out of the crater until further notice.

Mutnovsky consists of four coalescing stratovolcanoes of predominantly basaltic composition with multiple summit craters. Holocene activity has been characterized by slight to moderate phreatic and phreatomagmatic eruptions. There have been 18 reported eruptions since historical activity began in the 17th century. The most recent activity was from December 1960 to January 1961, when weak explosive eruptions sent a gas-and-ash column 3.5-4 km high.

Information Contacts: V. Kirianov, IVGG.

December 1996 (BGVN 21:12) Cite this Report

Fumarolic plume up to 1 km above the crater

On 25 November, a fumarolic plume was observed rising to a height of 1 km above the crater.

Information Contacts: 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; Vladimir Kirianov, Kamchatka Volcanic Eruptions Response Team (KVERT), Institute of Volcanic Geology and Geochemistry, Piip Ave. 9, Petropavlovsk-Kamchatsky, 683006, Russia.

April 2000 (BGVN 25:04) Cite this Report

Two short-lived gas-and-ash explosions on 17 March

Prior to 24 March 2000, KVERT (Kamchatkan Volcanic Eruption Response Team) had not included Mutnovsky in any activity reports this year. As of 28 April 2000, KVERT temporarily suspended operations because of a lack of funding.

After more precise analysis of visual reports from Petropavlovsk-Kamchatsky and a comparison of signals from several seismic stations, KVERT determined that at 0700 on 17 March, a short-lived explosion sent a gas-and-steam plume to heights of ~1,000 m above the volcano; the plume disappeared within 30 minutes. At 1300 on 17 March, another gas-and-steam plume rose to about the same altitude and extended to the SE; activity ended by 1700. A corresponding shallow seismic event was registered at 1856, followed by a low-frequency (1 Hz) volcanic tremor. The hazard level was originally Yellow but was returned to Green later in the month, although episodes of low-level, low-frequency volcanic tremor continued. The volcano occasionally was obscured by clouds.

An increase in volcanic tremor occurred on 1 April from 1300-2100 and again at 0930-1700 on 13 April. The volcano remained quiet through the rest of April.

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.

May 2000 (BGVN 25:05) Cite this Report

20 years of fumarolic increases precede 17 March eruption

Two minor phreatic explosions occurred at Mutnovsky on 17 March 2000 (see BGVN 25:04). Subsequent helicopter observations indicated that the eruption took place in the N crater of the volcano. This crater had been active prior to the middle 1950's, but was snow-and-ice filled over the last 20 years. The recent eruption produced small amounts of ash and blocks of altered rocks.

Clearly expressed precursors had provided strong indications that an eruption could be expected. In effect, scientists noted that over the last 20 years the heat output from the main crater increased and was accompanied by the appearance of new fumarolic grounds and an increase in the fumarolic temperature. They also detected a sudden activation of the alpine glacier had started about 5 years ago. Scientists also observed that during the last 5 years, the relative abundance of the chemical elements S/Cl and S/F in the water of Vulcannaya River, which drains the fumarolic fields of the NE and SE craters, increased 3- to 5-fold.

The low magnitude of the 16 March event, the seismicity which continued afterwards for several months, and the relatively long period of preparation may indicate that the explosion is merely a precursor to a stronger eruption in the near future.

Information Contacts: George Gavrilenko, Institute of Volcanology, Far East Division of the Russian Academy of Sciences, Petropavlovsk-Kamchatsky, 683006, Russia; Yuri Taran, Institute of Geophysics, UNAM, Mexico D.F. 04510 Mexico.

September 2000 (BGVN 25:09) Cite this Report

Small phreatic(?) eruption on 30 June and continued fumarolic activity

Fumarolic activity continued from June through mid-October 2000. Volcanic tremor was slightly above background levels until it increased markedly at 1800 on 26 June. At 0751 on 30 June, seismicity indicated a short-lived vigorous phreatic(?) eruption. By 4 July, volcanic tremor decreased to background levels. Weak fumarolic activity continued to be observed, and on 22 July, a fumarolic plume rose 200-300 m above the volcano. On the same day, two small volcano-tectonic earthquakes occurred between Mutnovsky and neighboring Gorely volcano. Near noon on 31 July, a fumarolic plume rose 500 m above the summit.

A single volcano-tectonic earthquake occurred under the volcano on 9 August. A gas-and-steam plume rose to a height of 200-300 m and drifted 5 km E. On 30-31 August, a gas-and-steam plume rose 100-500 m above the volcano and moved 1 km NW. Fumarolic plumes rose 200-500 m above the summit on 1 and 7 September. Occasional fumarolic activity continued throughout September with plumes reaching up to 300 m above the volcano. On 8 October, gas-and-steam explosions rose 800-1,000 m above Mutnovsky and drifted NW. The following day, similar explosions rose 300-600 m and the plume extended 2 km E.

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.