KVERT reported that during 18-21 February seismicity from Kizimen was high but variable, and many shallow volcanic earthquakes as well as volcanic tremor continued to be detected. Satellite images showed a bright thermal anomaly over the volcano daily during 18-25 February. Ash plumes drifted more than 200 km E during 21-24 February. The Aviation Color Code remained at Orange.

The Tokyo VAAC reported that on 25 February an eruption detected in satellite imagery produced a plume that rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted E. Subsequent notices stated that continuing ash emissions dissipated later that day. NASA's Earth Observatory posted a satellite image acquired on 25 February that showed steam and ash plumes drifting NE. Ash on the snow was visible NE, E, and SE of the volcano. The VAAC also noted that eruptions reported by KEMSD during 27 February-1 March produced plumes that rose to altitudes of 6.1-7.3 km (20,000-24,000 ft) a.s.l.

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), NASA Earth Observatory