KVERT reported that during 22-29 April seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 6.7 km (22,000 ft) a.s.l. Satellite imagery showed a thermal anomaly daily on the lava dome. According to ground-based observations during 22 and 25-27 April ash plumes rose to an altitude of 7.5 km (24,600 ft) a.s.l. and drifted N and SE. Satellite imagery showed ash plumes drifting 153 km N on 22 April and as far as 400 km SE during 23-24 and 27 April. KVERT noted that the Aviation Color Code remained at Orange. Based on information from KEMSD, the Tokyo VAAC reported that on 1 May an eruption produced a plume that rose to an altitude of 6.1 km (20,000 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)