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Maly Semyachik (russian: Малый Семячик) is a 
The water in the lake has an unusual bright turquoise color. It's because the waters of the lake are poisonous due to the content of several types of acids and other chemical compounds of the periodic table.
The water in the lake never freezes, even when everything is covered with a layer of ice and deep snow. The name "Semyachik" in translation from Itelmensky means "Stone Earth".
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
located in the eastern part of Kamchatka Peninsula, Russia. It is a compound stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
located in a 10-km-wide caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
within the 15x20 km mid- Pleistocene Stena-Soboliny caldera. Three overlapping stratovolcanoes were constructed sequentially along a NE-SW line, with the youngest cone, Tseno-Semyachik, at the southwest end. A hot, acidic crater lake fills the historically active Troitsky Crater, which formed during a large explosive eruption of Ceno-Semiachik about 400 years ago.
The water in the lake has an unusual bright turquoise color. It's because the waters of the lake are poisonous due to the content of several types of acids and other chemical compounds of the periodic table.
The water in the lake never freezes, even when everything is covered with a layer of ice and deep snow. The name "Semyachik" in translation from Itelmensky means "Stone Earth".
References
*{{cite gvp, vn=300140, name=Maly Semyachik Mountains of the Kamchatka Peninsula Volcanoes of the Kamchatka Peninsula Stratovolcanoes of Russia Volcanic crater lakes Calderas of Russia Pleistocene calderas