KVERT reported that during 3-8 December seismicity at Kizimen was above background levels. An increase in seismicity reported on 9 December was possibly caused by snow avalanches. That same day, the Tokyo VAAC reported that according to KEMSD an eruption produced a plume that rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted N. Ash was not identified in satellite images. The Level of Aviation Color Code remained at Yellow.

On 9 December, seismicity significantly increased and the Aviation Color Code level was raised to Orange. A bright thermal anomaly was observed in satellite imagery the next day. On 13 December an explosive eruption generated ash plumes that rose to altitudes of 3-3.5 km (9,800-11,500 ft) a.s.l. and drifted NW. Based on information from KEMSD and analysis of satellite imagery, the Tokyo VAAC reported that an ash plume rose to an altitude of 10 km (33,000 ft) a.s.l. and drifted N. KVERT noted that lightning in the ash plumes was observed. The Aviation Color Code was raised to Red. Ash deposits in Kozyrevsk and Tigil, 110 and 308 km NW, respectively, were 5 mm thick. Later that day seismic activity decreased; the Aviation Color Code was lowered to Orange.

Geological Summary. Kizimen is an isolated, conical stratovolcano that is morphologically similar to St. Helens prior to its 1980 eruption. The summit consists of overlapping lava domes, and blocky lava flows descend the flanks of the volcano, which is the westernmost of a volcanic chain north of Kronotsky volcano. The 2334-m-high edifice was formed during four eruptive cycles beginning about 12,000 years ago and lasting 2000-3500 years. The largest eruptions took place about 10,000 and 8300-8400 years ago, and three periods of long-term lava dome growth have occurred. The latest eruptive cycle began about 3000 years ago with a large explosion and was followed by intermittent lava dome growth lasting about 1000 years. An explosive eruption about 1100 years ago produced a lateral blast and created a 1.0 x 0.7 km wide crater breached to the NE, inside which a small lava dome (the fourth at Kizimen) has grown. Prior to 2010, only a single explosive eruption, during 1927-28, had been recorded in historical time.

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