KVERT reported that at 0921 and 1155 on 22 April ash plumes from Klyuchevskoy rose to altitudes of 5-5.5 km (16,400-18,000 ft) a.s.l. and drifted 130-140 km E, based on satellite and webcam data. KVERT noted that the ash content in the plumes had significantly increased compared to emissions first observed on 9 April. The Aviation Color Code was raised to 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)