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Photo glossary of volcano terms

Drained lava tube at Kilauea Volcano, Hawai`i

Photograph provided by
Hawai`i Volcanoes National Park

Thurston (Nahuku) lava tube near summit caldera of Kilauea Volcano in Hawai`i Volcanoes National Park

Lava tube
Lava tubes are natural conduits through which lava travels beneath the surface of a lava flow. Tubes form by the crusting over of lava channels and pahoehoe flows. A broad lava-flow field often consists of a main lava tube and a series of smaller tubes that supply lava to the front of one or more separate flows. When the supply of lava stops at the end of an eruption or lava is diverted elsewhere, lava in the tube system drains downslope and leaves partially empty conduits beneath the ground. Such drained tubes commonly exhibit "high-lava" marks on their walls, generally flat floors, and many lava stalactites that hang from the roof. Lava can also erode downward, deepening the tube and leaving empty space above the flowing lava.

Related photoglossary terms:


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U.S. Department of the Interior, U.S. Geological Survey, Menlo Park, California, USA
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Last modification: Monday, 04-Sep-2000 22:40:34 EDT (SRB)