KVERT reported that during 16-23 April seismic activity from Kliuchevskoi was above background levels. Strombolian activity was noted and lava continued to flow down the flanks. Gas-and-steam plumes rose to an altitude of 5.7 km (18,700 ft) a.s.l. Satellite imagery revealed a large daily thermal anomaly from the volcano, and ash plumes that drifted about 45 km S on 18 April. Gas-and-steam plumes drifted 90-100 km E on 20 and 21 April. Based on information from the Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 27 April an ash plume rose to an altitude of 7.9 km (26,000 ft) a.s.l. and drifted W. The Aviation Color Code level remained at Orange.

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