KVERT reported that during 22-29 October seismic activity at Kliuchevskoi was above background levels and Strombolian activity was observed. Satellite imagery analyses showed a large and intense daily thermal anomaly over the volcano and two lava flows descending the W and SW flanks from the summit crater. Ash plumes also detected in imagery drifted more than 2,300 km E. Ash plumes rose to altitudes of 8-9 km (26,200-29,500 ft) a.s.l. during 22-25 and 27 October. The Aviation Color Code level remained at Red. A news article from 29 October stated that ash from Kliuchevskoi and Shiveluch caused area flight diversions.

On 30 October explosive activity decreased along with the magnitude of volcanic tremor. Based on visual observations and analysis of satellite imagery, ash plumes rose to altitudes of 5-5.5 km (16,400-18,000 ft) a.s.l. and drifted 100 km SE. The Aviation Color Code level was lowered to Orange. The Tokyo VAAC reported that, based on analyses of satellite imagery and information from KVERT, eruptions on 31 October and 2 November, and a possible eruption on 1 November produced ash plumes that rose to altitudes of 5.2-6.7 km (17,000-22,000 ft) a.s.l. and drifted SE and E.

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