KVERT reported that seismic activity at Kliuchevskoi was above background levels during 28 November-10 December; Strombolian activity ejected bombs 500 m above the crater and lava effusion on the NW flank continued. Analysis of satellite imagery revealed a large daily thermal anomaly in the crater. During 27-29 November, and 2 and 4 December, gas-and-steam plumes with little ash content rose to altitudes of 6-6.2 km (19,700-20,300 ft) a.s.l. and drifted 40-115 km NE, E, SE, and SW. During 4-5 December, the ash content in plumes increased. On 8 December, phreatic bursts occurred where the lava flow front contacted the Erman Glacier. On 9 December, a 50-km-wide ash plume drifted about 550 km ENE. The Level of Concern Color Code was raised to Red. KVERT warned that the activity was dangerous for international and low-flying aircraft. On 10 December, the Level of Concern Color Code was lowered back to Orange because explosive activity decreased. A gas-and-steam plume with a small amount of ash drifted NE.

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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)