Due to increased volcanic activity at Karymsky, KVERT raised the Concern Color Code to Orange from Yellow on 29 August. On 29 August at 1240 and 1612 explosions occurred that produced ash plumes to heights of 4-4.7 km a.s.l. The plumes drifted E. During 22-29 August, seismicity was above background levels, with about 180 shallow earthquakes per day. These earthquakes indicated possible ash-and-gas explosions to heights of 1-1.5 km above the volcano.

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)