Report on Avachinsky (Russia) — 17 October-23 October 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 17 October-23 October 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Avachinsky (Russia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 17 October-23 October 2001. Smithsonian Institution and US Geological Survey.
53.256°N, 158.836°E; summit elev. 2717 m
All times are local (unless otherwise noted)
During 12-19 October gas-and-steam plumes rose above Avachinsky's crater and until 18 October seismicity was at background levels or was not registered. During 18 and 19 October a series of weak local earthquakes were detected ~700 m beneath the summit. On 17 October a fracture was observed in the lava dome that extended E-SE and W-NW, joining the hottest parts of the edifice. The fracture extended 100-150 m down the flanks of the cone.The volcano remained at Concern Color Code Yellow.
Geologic Background. Avachinsky, one of Kamchatka's most active volcanoes, rises above Petropavlovsk, Kamchatka's largest city. Avachinsky began to form during the middle or late Pleistocene and is flanked to the SE by the parasitic volcano Kozelsky, which has a large crater breached to the NE. It has a large horseshoe-shaped caldera, breached to the SW, that was formed when a major debris avalanche about 30,000-40,000 years ago buried an area of about 500 sq km to the south underlying the city of Petropavlovsk. Reconstruction of the volcano took place in two stages, the first of which began about 18,000 years before present (BP), and the second 7000 years BP. Most eruptive products have been explosive, with pyroclastic flows and hot lahars being directed primarily to the SW by the breached caldera, although relatively short lava flows have been emitted. The frequent historical eruptions have been similar in style and magnitude to previous Holocene eruptions.