KVERT reported that a thermal anomaly over Klyuchevskoy was identified in satellite images during 13-14 May.
Strong explosions began at 0315 on 15 May, and generated ash plumes that rose as high as 10.5 km (34,400 ft) a.s.l.
The ash clouds lingered around Klyuchevskoy and surrounding volcanoes for about eight hours before gradually dissipating.
Nighttime summit incandescence and a hot avalanche were noted.
The Aviation Color Code was raised to Orange.
Source: Kamchatkan Volcanic Eruption Response Team (KVERT)