KVERT reported that on 17 and 22 September a weak thermal anomaly over Karymsky was detected in satellite imagery. During 19-23 September seismic activity was above background levels; analyses of the seismic data indicated that ash plumes possibly rose to an altitude of 2 km (6,600 ft) a.s.l. during 21-22 September, and to an altitude of 4.5 km (14,800 ft) a.s.l. on 23 September. Scientists flying near Karymsky in a helicopter on 22 September saw ash plumes that rose to an altitude of 1.7 km (5,600 ft) a.s.l. and drifted E. The Level of Aviation Color Code was raised to 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)