Volcano Bolshoi Semiachik. Facts
Name: Bolshoi Semiachik
GVP Number: 300150
Synonims: Central Semiachik, Bol'shoy Semyachik, Burlyashchy, Zubchatka
Region: Kamchatka Peninsula
Volcanic Zone: Eastern Kamchatka
Coordinates: 54°18'57" N 160°1'32" E
Absolute Elevation: 1720 m
Status: Extinct
Location: The volcano is situated in the Eastern Kamchatka volcanic belt, Uson caldera is 20 km northeast, and Maly Semiachik volcano is 25 km southwest
Type: Extrusive complex
Composition: andesites, basalts, dacites, rhyodacites
Last known eruption: B.C. (Holocene)

Bolshoy Semyachik Volcano is a complex volcanic edifice with a caldera 10 km in diameter. The formation of the caldera is associated with the removal of large masses of ignimbrites covering the vicinity of the volcano. Post-caldera formations fill the caldera and cover its eastern side. Among them, there are eight cone-shaped stratovolcanoes with a base diameter from 3-4 to 8-9 km: Zubchatka, Baraniy, Problematichny, Plosky, Kulakov, Popkov, Burlyashchiy, Central Semyachik. The space between them is occupied by numerous domes and cinder cones with lava flows. The age of the volcano is Lower-Middle Pleistocene.

Леонов В.Л., Гриб Е.Н. Вулкан Большой Семячик / Действующие вулканы Камчатки. В 2-х т. Т. 2. М.: Наука. 1991. С. 144-159.
Леонов В.Л., Гриб Е.Н. Вулканический массив Большой Семячик, Камчатка: геологическое строение, структурная позиция // Вулканология и сейсмология. 2014. № 1. С. 3-19.
Related Resources
Holocene Kamchatka volcanoes