Seismicity was above background levels at Karymsky during 12-19 September, with 210-300 shallow earthquakes occurring per day. These data indicated that possible ash-and-gas explosions occurred and rose 1-1.5 km above the crater. On 14 September an ash-and-gas plume rose 0.5 km above the crater. On 23 September, after 2 days of low seismicity, an explosion occurred at 1808 that produced an ash plume to 5 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)