KVERT reported that a strong seismic event from Shiveluch was recorded on 4 December at 2100. Prior to the event, seismicity was at background levels and weak fumarolic activity was observed. According to video data from 5 December, explosions produced plumes that rose to an altitude of 4 km (13,100 ft) a.s.l. and drifted NW. Strong explosions from the lava dome were possible and avalanches to a distance of 3-5 km down the SW flank were noted. The Level of Concern Color Code was raised from Yellow to Orange.

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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)