A 25 April report on Shiveluch from KVERT stated that, based on seismic data a hot pyroclastic avalanche possibly took place on 23 April. Also, a M 2.25 earthquake occurred this day. Intermittent spasmodic volcanic tremor registered all week. According to visual data from Klyuchi, an ash plume rose 1,500 m above the dome on 24 April; gas and steam plumes rose 50-500 m above the dome on 19-21 and 24 April and the plumes blew 10 km to the E and SE, respectively. Clouds typically obscured the volcano on the other days.

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)