Volcano Zavaritsky Caldera. Facts
Name: Zavaritsky Caldera
GVP Number: 290180
Synonims: Zavaritzki Caldera, Midori
Region: Kuril Islands
Volcanic Zone: Central Kuriles
Coordinates: 46°56'3" N 151°57'12" E
Absolute Elevation: 624 m
Status: Active
Aviation Color Code: GREEN
Location: in the southern half of Simushir Island, the third mountain range from the north
Type: Caldera
Composition: pyroxene andesites
Last known eruption: 1957/11/12 - 1957/12/04
The central cone, formed into the caldera with a diameter of 7-8 km and a depth of 400 m, was largely destroyed by explosive eruptions. The western and northwestern slopes of the central cone, through a breakthrough of the outer caldera, descend to the shores of the Sea of Okhotsk, forming a rugged coastline with ledges of lava flows. The walls of the inner caldera, cut into the central cone, expose in the northern part the layered structure of a typical stratovolcano with some prevalence of pyroclastic material over the lavas. The composition of the rocks of the central cone varies over an extremely wide range: from basalts to dacites.
The inner caldera captured not only the apical part of the central cone, but also its southern foot and the adjacent part of the atrio, up to the slope of the outer caldera. At the bottom of the caldera is located Biryuzovoe lake, in 1958 its level was 40 m, and the depth reached 70 m. After 1916, an eruption occurred in the caldera: in the southern part of the destroyed old slag cone with a crater diameter of 350 m and a bottom of 250 m, an extrusive dome in size 100 x 140 m was forming. An effusive dome 200-300 m in size appeared 500 m east of the slag cone in the form of an Island, separated from the shore of the caldera lake by a strait 40 m wide.

Горшков Г.С. Вулканизм Курильской островной дуги / Отв. ред. Рудич К.Н. М.: Наука. 1967. 288 с.
Горшков Г.С. Кальдера Заварицкого // Бюллетень вулканологических станций. 1960. № 30. С. 30-49.
Горшков Г.С. Каталог действующих вулканов Курильских островов // Бюллетень вулканологических станций. 1957. № 25. С. 96-178.
Potencial Hazard
Ash clouds, ash falls, pyroclastic flows, hot avalanches and lahars are a potential hazard associated with explosive eruptions of this volcano. The volcano poses a potential hazard to international and local airlines passing in the Kuriles region, since the height of its ash emissions can reach 10-15 km above sea level, ash plumes and clouds can drift hundreds and thousands of kilometers from the volcano in different directions.
Related Resources
Active Volcanoes of Kamchatka and Kuriles