KVERT reported that during 11-22 May, seismic activity at Kliuchevskoi continued above background levels and a thermal anomaly in the crater was detected on satellite imagery. According to video data and visual observations, Vulcanian activity at the terminal crater and phreatic bursts at the NW flank of the volcano were observed on 11 and 16 May. Also on 11 and 16 May, ash plumes rose to 9.7 km (31,800 ft) a.s.l. and drifted E and NE, respectively. Clouds inhibited observation on other days. Ashfall was reported from the town of Klyuchi, about 30 km to the NE, during 11-12 and 16-17 May. KVERT raised the Level of Concern Color Code from Orange to Red on 17 May.

On 18 May, KVERT reported that deposits from a mudflow filled the Krivaya river. During 18-22 May, ash plumes rose to an altitude of 8.5 km (27,900 ft) a.s.l. Based on observations from satellite imagery, ash plumes drifted N, NE, NW, and E during 11-22 May.

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)