Based on visual observations and analyses of satellite data, KVERT reported that during 13-20 September a viscous lava flow effused onto the N and NW flanks of Shiveluch's lava dome, accompanied by hot avalanches, incandescence, ash explosions, and fumarolic activity. A thermal anomaly was detected in satellite images during 15-16 September; clouds obscured views on the other days. Video data showed that at 1454 on 20 September an ash plume rose to altitudes of 5-5.5 km (16,400-18,000) a.s.l. and drifted 20 km NE. 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)