KVERT reported that seismic activity at Karymsky was at background levels during 21-23 August and above background levels during 24-27 August. Possible explosions may have generated ash plumes to an altitude of 3.2 km (10,500 ft) a.s.l. Analysis of satellite imagery revealed a thermal anomaly in the crater during 24 and 26-28 August and that an ash plumes drifted SE on 27 August. The Level of Concern Color Code remained at Orange.

Based on analysis of satellite imagery and information from KEMSD, the Tokyo VAAC reported that on 29 August and 2 September eruption plumes rose to an approximate altitude of 3 km (10,000 ft) a.s.l.

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)