KVERT reported that explosive activity at Shiveluch continued during 11-18 May. Ground-based observers and satellite imagery indicated that a viscous lava flow continued to effuse in the active crater, and was accompanied by fumarolic activity and lava-dome incandescence. Satellite imagery during 10-12 and 15-16 May showed a thermal anomaly on the lava dome. On 12 May observers reported that ash plumes rose to an altitude of 8 km (26,200 ft) a.s.l. and satellite imagery showed an ash plume drifting more than 800 km E.

Based on information from KVERT and analyses of satellite images, the Tokyo VAAC reported that on 20 May an ash plume rose to an altitude of 9.1 km (30,000 ft) a.s.l. and drifted SW. Images the next day showed that the ash had dissipated.

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)