KVERT reported above-background seismicity at Kliuchevskoi during the week ending 1 May. Specifically, there were 25 earthquakes over M 1.25 at ~30 km depth, and 19 earthquakes over M 1.25 at shallower depths, including some within the edifice. In addition, during the same week instruments registered numerous weak, shallow earthquakes, and continuous spasmodic tremor. Residents in the city of Klyuchi saw various gas-and-steam plumes rising to these heights above the crater: on 25 April up to 300 m; and several other late April plumes up to ~ 2 km. The plume of 28 April extended over 5 km to the SE. Videos suggested that plumes escaping the crater in the early morning hours of 2 May could have contained ash.

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)