KVERT reported that seismic activity at Shiveluch was at background levels during 21-28 February. Based on interpretations of seismic data, ash plumes likely rose to an altitude of 5.5 km (18,000 ft) a.s.l. Lava flows continued to be active on the S and N flanks. Fumarolic activity was seen during 20-21 and 23-25 February. During 24-25 February, pilots reported dark plumes near the volcano that rose to altitudes of 5 km (16,400 ft) a.s.l. Analysis of satellite imagery revealed a daily thermal anomaly on the lava dome and an ash plume that drifted 40 km NNE on 25 February. The Level of Concern Color Code remained at Orange.

Based on information from KEMSD and analysis of satellite imagery, the Tokyo VAAC reported that eruptions on 25 February and 4 March produced plumes that rose to altitudes of 4.9-5.8 km (16,000-19,000 ft) a.s.l. The plumes drifted W on 25 February.

Geological Summary. The high, isolated massif of Sheveluch volcano (also spelled Shiveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group. The 1,300 km3 andesitic volcano is one of Kamchatka's largest and most active volcanic structures, with at least 60 large eruptions during the Holocene. The summit of roughly 65,000-year-old Stary Shiveluch is truncated by a broad 9-km-wide late-Pleistocene caldera breached to the south. Many lava domes occur on its outer flanks. The Molodoy Shiveluch lava dome complex was constructed during the Holocene within the large open caldera; Holocene lava dome extrusion also took place on the flanks of Stary Shiveluch. Widespread tephra layers from these eruptions have provided valuable time markers for dating volcanic events in Kamchatka. Frequent collapses of dome complexes, most recently in 1964, have produced debris avalanches whose deposits cover much of the floor of the breached caldera.

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