KVERT reported that during 2-9 December lava-dome extrusion onto Sheveluch’s N flank was accompanied by strong fumarolic activity, dome incandescence, ash explosions, and hot avalanches. Satellite images showed a thermal anomaly over the dome on clear days, and ash plumes drifting 60 km NW on 8 December.

On 10 December explosions generated ash plumes observed in satellite images that rose to altitudes of 10-11 km (32,800-36,000 ft) a.s.l. and drifted 320 km NNE and N. The Aviation Color Code was raised to Red. Satellite images later that day showed a thermal anomaly over the volcano but no ash emissions; the leading edge of the ash plume released earlier was 910 km NNE, drifting at an altitude of 11 km (36,000 ft). The Aviation Color Code was lowered 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)