KVERT reported that seismic activity at Kliuchevskoi was above background levels during 5-12 December. Strombolian activity ejected bombs 500 m above the crater and lava effusion on the NW flank continued. Phreatic bursts occurred where the lava flow front contacted the Erman Glacier. On 6 and 9 December, ashfall was reported in Klyuchi, about 30 km to the NE. Analysis of satellite imagery revealed a large daily thermal anomaly in the crater. Gas-and-steam plumes containing small amounts of ash rose to altitudes of 5-6 km (16,400-19,700 ft) a.s.l. and drifted more than 300 km E. During 8-10 December, ash plumes rose to altitudes of 7.5-8 km (24,600-26,200 ft) a.s.l. and drifted about 700 km E. The Level of Concern Color Code remained Orange.

Based on information from KVERT and analysis of satellite imagery, the Tokyo VAAC reported that during 13-15 December eruptions ash produced plumes to altitudes of 5.2-8.2 km (17,000-27,000 ft) a.s.l. Plumes drifted E and 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.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC), Kamchatkan Volcanic Eruption Response Team (KVERT)