KVERT reported that moderate seismic activity at Karymsky was detected during 16-23 August. Based on seismic interpretation by Kamchatka Branch of Geophysical Services (KBGS; Russian Academy of Sciences), possible ash plumes rose to an altitude of 4 km (13,100 ft) a.s.l. on 19 August and to an altitude of 2 km (6,600 ft) a.s.l. the other days of the week. Satellite imagery showed a weak thermal anomaly on the volcano on 17, 20, and 22 August. On 22 August a pilot observed an ash plume near the volcano; that same day an ash plume was visible in satellite images drifting 30 km ESE at altitudes of 1-1.5 km (3,300-4,900 ft) a.s.l. The Aviation Color Code 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.

Source: Kamchatkan Volcanic Eruption Response Team (KVERT)