KVERT reported that during 1-7 April seismic data at Shiveluch indicated that possible ash plumes rose to an altitude of 7.5 km (24,600 ft) a.s.l. Ground-based observations during 1-2 April indicated that gas-and-steam plumes containing ash rose to an altitude of 2.7 km (8,800 ft) a.s.l. A thermal anomaly on the lava dome was observed in satellite imagery those same two days. Ash plumes drifted in different directions as far as 187 km during 1-3 and 5 April. The Tokyo VAAC reported that on 7 April a possible eruption detected in satellite imagery produced a plume that rose to an altitude of 3.7 km (12,000 ft) a.s.l. Subsequent notices that day stated that ash continued to be detected, and then dissipated. The Aviation 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.

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