KVERT reported moderate levels of activity at Karymsky during 22-29 August. A weak thermal anomaly over the volcano was identified in satellite images during 26 and 28-29 August; weather clouds obscured views on the other days during the week. A series of six significant explosions beginning at 0810 on 30 August generated ash plumes that rose as high as 10 km (32,800 ft) a.s.l. and drifted NW, SE, and ENE. The Aviation Color Code was raised to Red (the highest level on a four-color scale). Pilots observed ash plumes rising 6-7 km (19,700-23,000 ft) a.s.l. and drifting ENE. At 0923 the Aviation Color Code was lowered to Orange. Dates are based on UTC times; specific events are in local time where noted.

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)