Volcanic unrest continued at Kliuchevskoi during 16-23 May. Seismicity was above background levels, with five M 2-2.1 earthquakes occurring at depths around 30 km during 15-21 May. Continuous spasmodic volcanic tremor occurred during the report period. Gas-and-steam plumes rose above the crater to low levels. On 18 May during 0000-0500, incandescence was visible above the volcano's crater from the town of Klyuchi. This is the first such observation since 1994. Thermal anomalies were visible on satellite imagery during 15-22 May. On 17 May ash deposits were visible on the volcano's E and SE flanks. Kliuchevskoi remained at Concern Color Code 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)