KVERT reported that seismic activity at Kliuchevskoi was above background levels during 15-18 and 26-27 January and at background levels during 19-21 January. Diffuse steam-and-gas plumes were noted. The magnitude of volcanic tremor rapidly decreased during 16-21 January. Analysis of satellite imagery revealed a weak daily thermal anomaly in the crater. The Level of Concern Color Code was lowered to Yellow. Strombolian activity in the summit crater was noted on 26 January. Ash plumes were seen drifting NE and E at altitudes of 5.3 km (17,400 ft) a.s.l. during 26-27 January, and were detected on satellite imagery drifting 80 km E at an altitude of 5.2 km (17,000 ft) a.s.l. on 27 January. The Level of Concern Color Code was raised to Orange.

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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)