Following the main eruptive period in early January, Karymsky had produced one to several small explosions a day. The explosions consisted mainly of steam with minor ash rising to heights <=1.5 km above the summit. Daily explosions continued until at least ~7 March. The lava flow erupted in January stopped growing during early February and continued cooling. The Institute of Volcanic Geology and Geochemistry (IVGG) reported that during the first week of March, Karymsky lake had a temperature of 23°C with a hotter area (32°C) located at its N end.

Ground reports noted one eruptive pulse at 2330 on 29 February; it sent ash and steam to ~4 km altitude; satellite imagery failed to detect this pulse. Simulated trajectory for plumes showed them generally blowing S to SSW.

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.

Information Contacts: Vladimir Kirianov and Yuri Doubik, IVGG; Alaska Volcano Observatory; Synoptic Analysis Branch, NOAA/NESDIS, USA.