KVERT reported that seismic activity from Shiveluch decreased on 27 December, but still remained above background levels. Based on video data, a steam-and-gas plume rose to 3.5 km (11,500 ft) a.s.l. on 27 December. On 28 December, ash plumes rose to 10 km (32,800 ft) a.s.l. and were seen on satellite imagery drifting E. The level of Concern Color Code was lowered to Orange.

Based on information from the Kamchatkan Experimental & Methodical Seismological Department (KEMSD) and satellite imagery, the Tokyo VAAC reported that eruptions produced plumes rising to 4.9-8.2 km (16,000-27,000 ft) a.s.l. on 1 and 2 January.

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)