View source for Pit crater

[[Image:Pit_crater.jpg|thumb|300px|Aerial view of Hi`iaka pit crater on the east rift zone of Kilauea Volcano, Hawai`i. The floor of the crater is covered by solidified lava that poured into the crater from the lower right (note black lava flow at crater rim).]]'''Pit craters''' are circular-shaped [[crater]]s formed by the sinking or collapse of the ground. Fissures may erupt from the walls or base of a '''pit crater''', but pit craters are not constructional features built by eruptions of lava or tephra. Pit craters may also partially fill with [[lava]] to form a [[lava lake]]. They are common along rift zones of shield volcanoes; for example, Mauna Loa and Kilauea volcanoes in Hawai`i. No one has observed the formation of a large pit crater, but they are thought to form as a consequence of the removal of support by withdrawal of underlying magma.<ref>http://volcanoes.usgs.gov/Products/Pglossary/PitCrater.html</ref>

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[[Category:Geology]]