An explosive Strombolian eruption began at Klyuchevskoy on 27 December and a bright thermal anomaly was identified in satellite images. On 30 December an ash plume rose as high as 6 km (19,700 ft) a.s.l. and drifted 195 km NW based on satellite and webcam images. KVERT raised the Aviation Color Code to Orange (the third level on a four-color scale). On 31 December explosions generated ash plumes that rose to 6.5 km (21,300 ft) a.s.l. and drifted 230 km WNW. A thermal anomaly persisted through 1 January, though explosions were not detected; the Aviation Color Code was lowered to Yellow. Dates are based on UTC times; specific events are in local time where noted.

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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)