On 1 February around 1000, a mudflow traveled ~6 km down Kliuchevskoi's NW flank into the Kruten'kaya River. The mudflow reached a height of a few meters and trees were covered with mud to about 1.5 m. Large blocks and trees were carried by the flow. A possible lava flow traveled down Krestovsky channel on the volcano's flank on 31 January.

During 28 January to 4 February, seismicity at Kliuchevskoi was above background levels, with a large number of shallow earthquakes occurring daily. Gas-and-steam plumes rose to ~1 km above the volcano's crater and drifted SW on 29 January and NW on January 31. A small amount of ash fell in Klyuchi on 31 January. 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)