Due to bad weather and poor visibility, monitoring . . . relied heavily on seismic observations. Through November and December the reported duration of tremor ranged from several hours/day (for the weeks ending 26 November and 4 December) to "background levels" (for the week ending 18 November). During the first week in December observers saw a gas-and-steam plume 500 m above crater rim, it was blown W and visible for a distance of ~15 km. Several other plume observations confirmed persistent degassing as late as the week of 22 December.

Geological Summary. Klyuchevskoy is the highest and most active volcano on the Kamchatka Peninsula. Since its origin about 6,000 years ago, this symmetrical, basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. It rises above a saddle NE of Kamen volcano and lies SE of the broad Ushkovsky massif. More than 100 flank eruptions have occurred during approximately the past 3,000 years, with most lateral craters and cones occurring along radial fissures between the unconfined NE-to-SE flanks of the conical volcano between 500 and 3,600 m elevation. Eruptions recorded since the late 17th century have resulted in frequent changes to the morphology of the 700-m-wide summit crater. These eruptions over the past 400 years have originated primarily from the summit crater, but have also included numerous major explosive and effusive eruptions from flank craters.

Information Contacts: V. Kirianov, IVGG.