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Volcanic crater

 
Volcanic Crater

 
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Volcanic crater
 
 
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A volcanic crater is a circular depression in the ground caused by volcanic activity. It is typically a basin, circular in form within which occurs a vent (or vents) from which magma
Magma

Magma is molten Rock that is found beneath the surface of the Earth, and may also exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and gas bubbles....
 erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth.






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Mount Cameroon Craters
A volcanic crater is a circular depression in the ground caused by volcanic activity. It is typically a basin, circular in form within which occurs a vent (or vents) from which magma
Magma

Magma is molten Rock that is found beneath the surface of the Earth, and may also exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and gas bubbles....
 erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth. During certain types of climactic eruptions, the volcano's magma chamber
Magma chamber

A magma chamber is a large underground pool of molten Rock lying under the surface of the earth's crust. The molten rock in such a chamber is under great pressure, and given enough time pressure can gradually fracture the rock around it creating outlets for the magma....
 may empty enough for an area above it to subside, forming what may appear to be a crater but is actually known as a caldera
Caldera

A caldera is a cauldron-like volcano feature usually formed by the collapse of land following a volcanic eruption such as the one at Yellowstone National Park....
.

Geomorphology

In the majority of typical volcanoes, the crater is situated atop the mountain formed from the erupted volcanic deposits such as lava flows and tephra
Tephra

Tephra is air-fall material produced by a Volcano regardless of composition or fragment size. Tephra is typically Rhyolite in composition, as most explosive volcanoes are the product of the more viscosity felsic or high silica magmas....
. Volcanoes that terminate in such a summit crater are usually of a conical form. Other volcanic craters may be found on the flanks of volcanoes, and these are commonly referred to as flank craters. Some volcanic craters may fill either fully or partially with rain and/or melted snow, forming a crater lake
Crater Lake

Crater Lake is a caldera lake located in the U.S. state of Oregon. It is the main feature of Crater Lake National Park and famous for its deep blue color and water clarity....
.

Some volcanoes, such as maar
Maar

A maar is a broad, low-relief volcanic crater that is caused by a phreatomagmatic eruption, an explosion caused by groundwater coming into contact with hot lava or magma....
s, consist of a crater alone, with scarcely any mountain at all. These volcanic explosion craters are formed when magma rises through water-saturated rocks and causes a phreatic eruption
Phreatic eruption

A Phreatic eruption, also called an ultravulcanian eruption, occurs when rising magma makes contact with ground water or surface water. The extreme temperature of the magma causes near-instantaneous evaporation to steam resulting in an explosion of steam, water, ash, rock, and volcanic bombs....
. Volcanic craters from phreatic eruptions often occur on plains away from other obvious volcanoes.

Footnotes


See also

  • Volcano
    Volcano

    A volcano is an opening, or rupture, in a planet's surface or Crust , which allows hot, molten rock, ash, and gases to escape from below the surface....
  • Caldera
    Caldera

    A caldera is a cauldron-like volcano feature usually formed by the collapse of land following a volcanic eruption such as the one at Yellowstone National Park....