KVERT reported that during 25 March-1 April seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 3.7 km (12,100 ft) a.s.l. A thermal anomaly on the lava dome was observed in satellite imagery during 25-29 March, and ash plumes drifted 57 km SE on 26 March. Ground-based observers noted that ash-and-gas plumes rose to an altitude of 5.5 km (18,000 ft) a.s.l. during 25-30 March.

Based on information from KEMSD and analyses of satellite imagery, the Tokyo VAAC reported that on 5 April an eruption produced a plume that rose to an altitude of 7.6 km (23,000 ft) a.s.l. and drifted N. A possible eruption detected in satellite imagery the next day produced a plume that rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted NE.

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