KVERT reported that during 19-26 June seismic activity from Shiveluch was above background levels. Based on interpretations of seismic data, steam-and-gas plumes with some ash content were emitted during the reporting period; ash plumes possibly rose to an altitude of 6.8 km (20,000 ft) a.s.l. On 20 June, ash plumes seen on a video camera rose to an altitude of 5 km (16,400 ft) a.s.l. Gas-and-steam activity was observed at other times during the reporting period. Analysis of satellite imagery revealed a daily thermal anomaly over the lava dome. Ash plumes were also seen on satellite imagery drifting 114 km S during 20 and 22-24 June and more than 100 km SW and NE on 25 June. A pyroclastic flow occurred on 25 June. The Level of Concern Color Code remained at Orange. Based on analysis of satellite imagery and information from KEMSD, the Tokyo VAAC reported that during 27-28 and 30 June eruptions produced plumes that rose to altitudes of 4.9-7 km (16,000-23,000 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: Tokyo Volcanic Ash Advisory Center (VAAC), Kamchatkan Volcanic Eruption Response Team (KVERT)