KVERT reported that seismic activity at Shiveluch was above background levels during 14-21 September. During 14-15 and 17-20 September, avalanches occurred and ash plumes rose to altitudes of 3.5-5.5 km (11,500-18,000 ft) a.s.l. Observations of video data indicated that gas-and-ash plumes rose to an altitude of 3.3 km (10,800 ft) a.s.l. and drifted NE and E on 14 and 15 September. Gas-and-steam plumes were noted on 13, 18, and 19 September. A thermal anomaly was present in the crater on satellite imagery during the reporting period. The Level of Concern Color Code 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)