KVERT reported that seismic activity at Shiveluch was above background levels during 26 September-3 October. A large number of hot avalanches descended the lava dome and produced ash plumes that rose to altitudes of 4-5 km (13,100-16,400 ft) a.s.l. On 28 September, an ash plume that was visible on a web camera rose to an altitude of about 5 km (16,400 ft) a.s.l. Based on interpretations of seismic data, ash explosions likely occurred on 28 September and 1 October and generated ash plumes that rose to an altitude of 7.5 km (24,600 ft) a.s.l. Ashfall was reported in Klyuchi (about 45 km SW) on 1 October. Analysis of satellite imagery revealed a thermal anomaly on the lava dome during 28 September and 1-2 October. 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)