Eruptions continued at Kliuchevskoi during late 2002 through mid-2003, with typical plume heights estimated at several hundred meters and occasionally reaching ~2 km above the volcano (eg., early July and August 2003). Above-background seismicity prevailed during most or all the reporting interval.

The volcano (also spelled Klyuchevskoy) was last reported on in BGVN 28:02, and vol. 27, no. 11, issues discussing events through 4 March 2003. This report relies heavily on tabled data to convey observations from as far back as 3 December 2002, providing some further details during the 3 December-4 March 2003 interval of overlap with the earlier reports. The source reports came from the Kamchatkan Volcanic Eruption Response Team (KVERT) and were communicated via the Alaska Volcano Observatory (AVO). Table 9 summarizes recent plume observations, while table 10 summarizes recent earthquake and intermittent spasmodic volcanic tremor, basically above-background seismicity affiliated with ongoing eruptive unrest.

Table 9. Plumes visible at Kliuchevskoi during December 2002 through mid-April 2003. Courtesy KVERT.

Table 10. Earthquakes and intermittent spasmodic volcanic tremor registered at Kliuchevskoi during December 2002 through mid-April 2003. Courtesy of KVERT.

Unrest continued during June 2003. Seismicity was above background and continuous spasmodic volcanic tremor tended to increase slowly and consistently. Earthquakes, both at 30 km and shallow depths, continued to register. The character of seismicity also indicated that weak gas-ash explosions possibly occurred. Table 11 summarizes thermal observations.

Table 11. Kliuchevskoi thermal anomalies and plumes observed via Russian and United States satellites, 2 June-11 August 2003. Courtesy of KVERT.

Geological Summary. Klyuchevskoy (also spelled Kliuchevskoi) is Kamchatka's highest and most active volcano. Since its origin about 6000 years ago, the beautifully symmetrical, 4835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of sharp-peaked Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during the past roughly 3000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 m and 3600 m elevation. The morphology of the 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

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.