Seismic activity at Karymsky was above background levels during 15-22 April, with 250-500 shallow earthquakes occurring daily. During 14-15 April, possible ash-and-gas explosions rose to 1.5 km above the crater (10,000 ft a.s.l.). Strombolian activity was observed on the evening of 20 April. Volcanic bombs rose to 50 m above the crater (5,200 ft a.s.l.). On 21-22 April ash-and-gas bursts rose 300-400 m above the crater (6,000-6,400 ft. a.s.l.). Ash fell to the NE on 21 April. Karymsky remained at Concern Color Code 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)