Seismicity remained above background levels at Karymsky during 25 October to 1 November, with ~250 shallow earthquakes occurring per day. The character of the seismicity indicated that ash-and-gas explosions reached heights of 1 km above the volcano and vigorous 5- to 10-minute-long gas emissions possibly occurred. Thermal anomalies were visible on satellite imagery during 26-28 and 30 October. On the 31st at 1350 a pilot reported seeing an ash plume at a height of ~4 km a.s.l. extending SE. Seismic data from the Kamchatkan Experimental and Methodical Seismological Department revealed that the character of seismicity changed after 1400 that day. The data indicated that a lava flow probably traveled down the volcano's slope. A bright, large thermal anomaly was visible at the volcano on satellite imagery at 1314, as well as a ~60-km-long plume extending to the WSW. Pilots saw plumes on 1 November at 1100 rising to 4 km a.s.l. and drifting to the SE, and on 2 November at 0920 rising to 5.2 km a.s.l. Karymsky remained at Concern Color Code Yellow.

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)