Report on Avachinsky (Russia) — December 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 12 (December 1990)
Managing Editor: Lindsay McClelland.
Avachinsky (Russia) Explosions feed 4-5-km tephra clouds; lava in crater; flank mudflows
Please cite this report as:
Global Volcanism Program, 1990. Report on Avachinsky (Russia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:12. Smithsonian Institution.
53.256°N, 158.836°E; summit elev. 2717 m
All times are local (unless otherwise noted)
An eruption began on 13 January with explosions at 1158 and 1203 that ejected ash clouds to 4-5 km above the crater. Ash fell on Petropavlovsk, roughly 30 km SSW. Lava was observed in the crater and small mudflows moved down the flanks. No pre-eruption seismicity was recorded, but seismic activity associated with the eruption was increasing as of 17 January.
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.
Information Contacts: B. Ivanov, IV.