KVERT reported that moderate seismic activity from Shiveluch was detected during 16-23 December and a large thermal anomaly over the volcano was observed in satellite imagery. Seismic data suggested that possible ash plumes rose to an altitude of 5 km (17,400 ft) a.s.l. Gas-and-steam plumes containing ash drifted 250 km S during 19-20 December. Explosions produced ash plumes that rose to an altitude of 6 km (19,700 ft) a.s.l. on 19 December. Ground-based observers noted that a viscous lava flow continued to effuse in the crater formed during a 2010 eruption. Moderate fumarolic activity at the lava dome was observed during 18-21 December; cloud cover prevented observations on the other days. The Aviation Color Code level remained at 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)