KVERT reported that seismic activity continued at a moderate level at Karymsky during 9-15 September, and indicated that possible ash plumes rose to an altitude of 4.6 km (15,100 ft) a.s.l. during 13-14 September. An observer in the area noted that ash explosions produced ash plumes all week that did not rise higher than 3.5 km (11,500 ft) a.s.l. A thermal anomaly was detected daily in satellite imagery and ash plumes drifted 80 km E and SE during 11-12 and 14 September. The Aviation Color Code remained at Orange.

Based on information from Yelizovo Airport (UHPP), the Tokyo VAAC reported that on 20 September an ash plume rose to an altitude of 2.7 km (9,000 ft) a.s.l. and drifted NE.

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)