Seismic activity was above background levels at Karymsky during 8-15 October, with 310-540 shallow events occurring daily. Interpretations of seismic data suggested that weak ash-and-gas explosions occurred during the week. Ash-and-gas plumes may have reached heights of 2.5-3 km a.s.l. on 9, 12, and 13 October. Ash plumes were visible on satellite imagery on 11 and 12 October, extending E then ESE 80 and 50 km, respectively. Karymsky remained at Concern Color 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)