During 22-29 November, KVERT decreased the Concern Color Code at Shiveluch from Orange to Yellow. Seismicity remained above background levels during the report interval and seismic data indicated that there had been hot avalanches and eight ash-and-gas explosions in which clouds reached 1-2 km above the lava dome (the previous week there were 19 ash-and-gas explosions to 2-3 km above the lava dome). Weak intermittent spasmodic tremor was registered during 24-25 November. Gas-and-steam plumes were seen rising 100-800 m above the lava dome and thermal anomalies were visible on satellite imagery.

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)