KVERT reported that during 2-9 October seismic activity from Kliuchevskoi was above background levels; many earthquakes and weak tremor were detected. Satellite imagery revealed a weak thermal anomaly over the volcano. During 2-3 October, Strombolian eruptions sent tephra 70-100 m above the crater and fumarolic activity was noted. On 7 October a fumarolic plume containing some ash rose to an altitude of 5.7 km (19,700 ft) a.s.l. The Level of Aviation 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)