KVERT reported that on 18 and 20 December seismic activity at Karymsky was at background levels; possible explosions may have generated ash-and-gas plumes to an altitude of 3 km (9,800 ft) a.s.l. on 18 December. Analysis of satellite imagery revealed a thermal anomaly in the crater during 21-26 December and ash plumes that drifted 80 km E during 21-23 December. Ash deposits 26 km long to the SE and 9 km long to the NE were noted on 21 December. The Level of Concern 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)