KVERT reported that Strombolian and sometimes Vulcanian activity at Klyuchevskoy continued during 18-25 December and lava advanced down the Kozyrevsky drainage on the S flank. Lava first flowed down the S flank on 8 December. A large bright thermal anomaly was identified daily in satellite images. Steam-and-gas plumes with some ash rose to 6 km (19,700 ft) a.s.l. and drifted 340 km mainly E. The Kamchatka Volcanological Station field team visited the area on 24 December to do work on field stations. They observed explosions that ejected incandescent material 300 m above the crater rim. A growing cinder cone in the summit crater was about 75 m higher than part of the crater rim. The lava flow ended at about 3,700 m elevation and spalled off incandescent material, descending an additional 350 m. The Aviation Color Code remined at Orange (the second highest level on a four-color scale).

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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Kamchatka Volcanological Station