KVERT reported that seismic activity at Shiveluch was at background levels during 15-17 and 21 May and above background levels the other days during 16-23 May; gas-and-ash explosions may have occurred on 18, 19, and 20 May. According to video footage and visual observations, small hot avalanches descended the lava dome every day and fumarolic activity was noted. A large hot avalanche caused an ash plume to rise to an altitude of 4 km (13,100 ft) a.s.l. on 20 May. The plume drifted E. Observations of satellite imagery revealed that a thermal anomaly was present in the crater daily and an ash-and-steam plume drifted more than 100 km SE on 20 May.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT) – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”