Avacha Volcano
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Avacha Volcano (Avacha, Avachinsky) (Russian: ) is an active volcano on the Kamchatka Peninsula in the far east of Russia. It lies within sight of the capital of Kamchatka Oblast, Petropavlovsk-Kamchatsky. Together with neighbouring Koryaksky volcano, it has been designated a Decade Volcano, worthy of particular study in light of its history of explosive eruptions and proximity to populated areas.
Geological history
Avachinsky lies on the Pacific Ring of Fire, at a point where the Pacific Plate is sliding underneath the Eurasian Plate at a rate of about 80 mm/year. A wedge of mantle material lying between the subducting Pacific Plate and the overlying Eurasian Plate is the source of dynamic volcanism over the whole Kamchatka Peninsula.
The volcano is one of the most active volcanoes on the Kamchatka Peninsula, and began erupting in the middle to late Pleistocene era. It has a horseshoe-shaped caldera, which formed 30-40,000 years ago in a major landslide which covered an area of 500 km² south of the volcano, underlying the city of Petropavlovsk-Kamchatsky. Reconstruction of a new cone inside the caldera occurred in two major eruption phases, 18,000 and 7,000 years ago.
Recent activity
Avachinsky has erupted at least 17 times in recorded history. Eruptions have generally been explosive, and pyroclastic flows and lahars have tended to be directed to the south west by the breached caldera. The most recent large eruption (VEI=4) occurred in 1945, when about 0.25 km³ of magma was ejected. The volcano has since had small eruptions in 1991 and 2001.
The volcano continues to experience frequent earthquakes, and many fumaroles exist near the summit. The temperature of gases emitted at these fumaroles has been measured at over 400°C. In light of its proximity to Petropavlovsk-Kamchatsky, Avachinsky was designated a Decade Volcano in 1996 as part of the United Nations' International Decade for Natural Disaster Reduction, together with the nearby Koryaksky volcano.
References
- Droznin D., Levin V., Park J., Gordeev E. (2002), Detailed Mapping of Seismic Anisotropy Indicators in Southeastern Kamchatka, American Geophysical Union, Fall Meeting 2002
- Levin V., Park J., Gordeev E., Droznin D. (2002), Complex Anisotropic Structure of the Mantle Wedge Beneath Kamchatka Volcanoes, American Geophysical Union, Fall Meeting 2002
- Taran Y.A., Connor C.B., Shapar V.N., Ovsyannikov A.A., Bilichenko A.A. (1997), Fumarolic activity of Avachinsky and Koryaksky volcanoes, Kamchatka, from 1993 to 1994, Bulletin of Volcanology, v. 58, p. 441-448
External links
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