Volcanic crater
From Wikipedia, the free encyclopedia
A volcanic crater is a conspicuous feature of many volcanoes, especially those currently or recently active. It is typically a basin of a roughly circular form within which occurs a vent (or vents) from which magma 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 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.
[edit] 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. 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.
Some volcanoes, such as maars, 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. Volcanic craters from phreatic eruptions often occur on plains away from other obvious volcanoes.
[edit] Volcanic craters of the solar system
Volcanic craters have also been identified on the Moon, Mars, Venus, and Io.
[edit] See also
ca:Cràter volcànic de:Vulkankrater et:Kraater es:Cráter volcánico eo:Vulkana kratero fr:Cratère volcanique is:Eldgígur it:Cratere vulcanico sw:Kasoko ya volkeno lt:Krateris ja:火口 nds:Vulkankrater pl:Krater wulkaniczny pt:Cratera vulcânica sk:Sopečný kráter sl:Vulkanski krater sv:Vulkankrater
