KVERT reported that during 22-30 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 containing small amounts of ash were seen on 22 April. Similar plumes rose to an altitude of 7.3 km (23,900 ft) a.s.l. during 25-27 April, and drifted W and SW. Satellite imagery revealed a large daily thermal anomaly from the volcano. An ash plume drifted about 65 km W on 24 April, and gas-and-steam plumes drifted 55 km W and SW during 24-27 April. Based on analyses of satellite imagery, the Tokyo VAAC reported that on 3 May a possible eruption produced a plume that rose to an altitude of 4.9 km (16,000 ft) a.s.l. and drifted W. The Aviation Color Code level remained at Orange.

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.

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