KVERT reported that during 14-21 May seismic activity from Karymsky was above background levels, suggesting that possible ash plumes rose to an altitude of 2.5 km (8,200 ft) a.s.l. Satellite imagery revealed a thermal anomaly over the volcano during 13-17 and 19-20 May, and an ash plume that drifted 18 km NE on 17 May. Based on information from the Yelizovo Airport (UHPP) and KVERT, the Tokyo VAAC reported that on 22 and 25 May ash plumes rose to an altitude of 4.3 km (14,000 ft) a.s.l. and drifted SW and W. The Aviation Color Code level remained at Orange.

Geological Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed during the early Holocene. The caldera cuts the south side of the Pleistocene Dvor volcano and is located outside the north margin of the large mid-Pleistocene Polovinka caldera, which contains the smaller Akademia Nauk and Odnoboky calderas. Most seismicity preceding Karymsky eruptions originated beneath Akademia Nauk caldera, located immediately south. The caldera enclosing Karymsky formed about 7600-7700 radiocarbon years ago; construction of the stratovolcano began about 2000 years later. The latest eruptive period began about 500 years ago, following a 2300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been vulcanian or vulcanian-strombolian with moderate explosive activity and occasional lava flows from the summit crater.

Sources: Tokyo Volcanic Ash Advisory Center (VAAC), Kamchatkan Volcanic Eruption Response Team (KVERT)