KVERT reported that during 8-15 October seismic activity from Kliuchevskoi was above background levels and lava from the summit crater flowed down the SW and W flanks. Satellite imagery analyses showed a large and intense daily thermal anomaly over the volcano. Strombolian activity was observed during 7-11 October. Daily gas-and-steam plumes rose to an altitude of 5.8 km (19,000 ft) a.s.l., but on 11 October the plumes rose to an altitude of 7.8 km (25,600 ft) a.s.l. Ash plumes seen in satellite imagery drifted 90 km NE and E during 10 and 12-14 October. The Tokyo VAAC reported that ash was seen in satellite imagery on 16 October. The next day possible eruptions reported by KVERT, and seen in satellite imagery, produced plumes that rose to altitudes of 5.2-5.8 km (17,000-19,000 ft) a.s.l. and drifted SE. Ash seen in imagery on 18 October may have been from an eruption earlier that day. Ash again seen in satellite imagery from a possible eruption on 19 October rose to an altitude of 6.1 km (20,000 ft) a.s.l. and drifted N. 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: Tokyo Volcanic Ash Advisory Center (VAAC), Kamchatkan Volcanic Eruption Response Team (KVERT)