KVERT reported that seismic activity at Shiveluch was moderate during 30 September-7 October. Ash plumes rose to altitudes of 6-9 km (19,700-30,000 ft) a.s.l. during 3-5 October, followed by new lava-dome extrusion. Seismicity indicated that possible ash plumes rose to altitudes of 4.5-5 km (14,800-16,400 ft) a.s.l. during 5-6 October; ground-based observers noted that ash plumes rose to an altitude of 5 km (16,400 ft) a.s.l. on those same days. Satellite imagery showed a large and bright thermal anomaly on the lava dome on 5 October and ash plumes that drifted 100 km NE on 6 October. The Aviation Color Code was lowered to Orange.

Based on information from KEMSD, the Tokyo VAAC reported that on 8 October an eruption produced a plume that rose to an altitude of 7 km (23,000 ft) a.s.l. and drifted E. Subsequent satellite images that day showed that ash was present and then had dissipated. An eruption on 10 October produced a plume that rose to an altitude of 7.3 km (24,000 ft) a.s.l.

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.

Sources: Kamchatkan Volcanic Eruption Response Team (KVERT), Tokyo Volcanic Ash Advisory Center (VAAC)