1000-10
Avachinsky
53°15' N, 158°50' E; summit elev. 2,741 m
Fig.1
Fig.2
Fig.3
Fig.4
Fig.5
Fig.6
Fig.7
Avachinsky, one of Kamchatka's most active volcanoes, rises above Petropavlovsk, Kamchatka's largest city (Fig. 1). Avachinsky consists of a late Pleistocene edifice, destroyed by a large horseshoe-shaped crater, which encloses the Young Cone stratovolcano (Figs.1-4). The crater is believed to have formed ~30,000 years ago as a result of a sector collapse(s). Deposits of the resulting debris avalanche(s) underlie the present city. Avachinsky's edifice resembles the Somma-Vesuvius complex, that is why the old part of Avachinsky sometimes is called Avachinsky Somma.
Holocene activity of the volcano started about 7250 14C yrs B.P. after a long repose period. During the first stage of its life (7250-3500 14C yrs B.P) Avachinsky produced explosive eruptions with pumice-falls and pyroclastic flows. At this time the eruptive center was probably formed by coalescent extrusive domes nested in the late Pleistocene collapse crater.(similar to modern Young Shiveluch). Tephra of these eruptions can be traced at a distance of more than 200-400 km. Volcanic material was dominated by low-K andesite (Figs.5 and 6).
About 3500 14C yrs BP the composition of the products shifted to basaltic andesites and frequent eruptions gave the birth to the Young Cone, located in the late Pleistocene crater. One of the initial explosive eruptions AV1 produced more than 4 km3 of basaltic andesite tephra which was dispersed at a distance of more than 300 km to the north and formed one of the main marker tephra layers for this area. The Young Cone produced multiple explosive (Fig. 7) and effusive eruptions, most recently in 1991 (Figs. 3 and 4) and 2001.
Pyroclastic flow deposits fill most of the valleys on the volcano's slopes (Fig.5). Tephra layers are well seen at the foot of the volcano (Fig. 6), some of them can be traced at a distance of more than 200-400 km away from the volcano and represent good markers for the Holocene stratigraphy (Braitseva et al., 1997, 1998).
Volcanic hazards associated with future eruptions from Avachinsky are shown on the map (Bazanova et al., 2001).
Literature
Bazanova LI, Braitseva OA, Puzankov MYu, Sulerzhitskiy LD (2003) Catastrophic plinian eruptions of the initial phase of the Avachinsky volcano Young Cone formation (Kamchatka, Russia). Volcanol Seismol (5): 20-40 [in Russian]
Bazanova LI, Braitseva OA, Melekestsev IV, Sulerzhitskiy LD. (2004) Catastrophic eruptions of Avachinsky volcano (Kamchatka) in Holocene: chronology, dynamics, geological and geomorphological effect, environmental impact and long-term forecast. Volcanol Seismol (6): 3-8 [in Russian]
Braitseva OA, Bazanova LI, Melekestsev IV, Sulerzhitskiy LD (1998) Large Holocene eruptions of Avacha volcano, Kamchatka (7250-3700 14C years B.P.). Volcanol Seismol 20 (1): 1-27
Braitseva OA, Melekestsev IV, Ponomareva VV, Sulerzhitsky LD (1995) The ages of calderas, large explosive craters and active volcanoes in the Kuril-Kamchatka region, Russia. Bull Volcanol 57 (6): 383-402
Braitseva OA, Ponomareva VV, Sulerzhitsky LD, Melekestsev IV, Bailey J (1997) Holocene key-marker tephra layers in Kamchatka, Russia. Quatern Res 47 (2): 125-139
Ivanov BV, Flerov GB, Masurenkov Yu.P., Kiriyanov V.Yu., Melekestsev IV, Taran Yu.A., Ovsyannikov AA (1996) The 1991 eruption of Avacha volcano: dynamics and the composition of eruptive products. Volcanol Seismol 17 (4-5): 369-394
Masurenkov Yu.P., Yegorova IA, Puzankov M.Yu., Balesta ST, Zubin MI (1991) Avachinsky volcano. In: Fedotov SA and Masurenkov YuP (Eds) Active volcanoes of Kamchatka. V. 2. "Nauka Publishers", Moscow, pp 246-273 [in Russian and English]
Melekestsev IV, Litasova SN, Sulerzhitsky LD (1992) On the age and scale of the directed-blast catastrophic eruption of the Avachinsky volcano (Kamchatka) in the Late Pleistocene. Volcanol Seismol 13 (2): 135-146
Melekestsev IV, Braitseva OA, Dvigalo VN, Bazanova LI (1994) Historical eruptions of Avacha volcano, Kamchatka. Attempt of modern interpretation and classification for long-term prediction of the types and parameters of future eruptions. Part 1. (1737-1909). Volcanol Seismol 15 (6): 649-666. Part 2. (1926 -1991). Volcanol Seismol 16 (2): 93-114
Puzankov M.Yu., Bazanova L.I., Maximov A.P., Moskalyova S.V. (2004) The initial plinian basic andesite eruptions of the Young cone, Avachinsky volcano (Kamchatka). Linkages among tectonics, seismicity, magma genesis, and eruption in volcanic arcs. IV International Biennial Workshop on Subduction Processes emphasizing the Japan-Kurile-Kamchatka- Aleutian Arcs. Petropavlovsk-Kamchatsky. August 21-27, P. 158-160, http://kiska.giseis.alaska.edu/kasp/kasp04/abstracts/puzankov.pdf