Report on Avachinsky (Russia) — 31 October-6 November 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 October-6 November 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, 31 October-6 November 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 26 October to 2 November seismicity was at background levels, with only weak earthquakes detected (magnitudes less than or equal to 1.2). During 29 October to 1 November, when the volcano was visible, weak-to-powerful gas-and-steam emissions were observed extending to the SE and E. The Concern Color Code was reduced from Yellow to Green.
Geologic Background. Avachinsky, one of Kamchatka's most active volcanoes, rises above Petropavlovsk, Kamchatka's largest city. It 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. A large horseshoe-shaped caldera, breached to the SW, was created when a major debris avalanche about 30,000-40,000 years ago buried an area of about 500 km2 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.