KVERT reported that during 1-8 October seismic activity from Kliuchevskoi was above background levels and lava from the summit crater flowed down the SW flank. Satellite imagery analyses showed a large and intense daily thermal anomaly over the volcano. Strombolian activity was observed almost every day, and gas-and-ash plumes rose to an altitude of 6.3 km (20,700 ft) a.s.l. Ash plumes seen in satellite imagery drifted 50 km SE during 5-6 October. The Aviation Color Code level remained at Orange. Based on analyses of satellite imagery and information from KVERT, the Tokyo VAAC reported ash drifting NE on 11 October. The next day an eruption seen in satellite imagery produced an ash plume that rose to an altitude of 10.1 km (33,000 ft) a.s.l. and drifted E. A subsequent notice stated that ash had dissipated. The Aviation Color Code level remained at 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)