Seismic activity at Karymsky was slightly above background levels during 1-8 June. According to visual observations, a gas-and-steam plume was visible on 5 June. KVERT lowered the Level of Concern Color Code from Orange to Yellow.

On 9 June, seismic data indicated that an explosion may have produced an ash plume that rose to an altitude of 3.8 km (12,500 ft) a.s.l. Strong seismicity and further possible explosions or avalanches followed the event. Clouds obscured summit observations. The Level of Concern Color Code was raised to Orange.

Based on information from KEMSD, the Tokyo VAAC reported that eruption plumes rose to 3.7-7 km (12,000-23,000 ft) a.s.l. during 9-12 June. Ash was not identified on satellite imagery.

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