An increase in seismicity at Kliuchevskoi during 13 November to at least 16 November led KVERT to raise the Concern Color Code from Green to Yellow. On 13 November at 1619 seismicity sharply increased from background levels when a swarm of shallow earthquakes began; these had magnitudes less than or equal to 3. During 13-15 November more than 150 earthquakes occurred with magnitudes less than or equal to 1.7. Prior to the seismicity increase, on 9 November a steam plume rose 600 m above the crater and during 11-13 November gas-and-steam plumes rose 50-100 m above the crater.

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)