Seismic activity at Kliuchevskoi continued at above background levels during 16-22 February. Based on observation and video data, gas-and-steam plumes rose to an altitude of 5.3 km (17,400 ft) a.s.l. and drifted E. These plumes possibly contained some ash. A thermal anomaly at the summit was seen on satellite imagery during 16-19 and 21 February. Based on information from KEMSD and satellite imagery, the Tokyo VAAC reported that eruption plumes possibly reached altitudes of 6.1 km (20,000 ft) a.s.l. and drifted E during 22-23 February.

According to a news article, ash particles up to 2 mm in diameter fell on the village of Klyuchi, about 40 km N on 26 February.

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), Tokyo Volcanic Ash Advisory Center (VAAC), RIA Novosti