KVERT reported that much like the previous week, the character of the volcanic activity did not change during 15-22 December. On 15 and 20 December weak seismicity was registered at the volcano and at 2105 on 15 December a seismic event was likely accompanied by a gas-and-ash explosion that sent a cloud to an inferred height of 2 km a.s.l. On 20 December a gas-and-steam plume rose 200-300 m above the crater. KVERT lowered the Concern Color Code from Yellow to Green.

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)