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a fissure in the earth's crust (or in the surface of some other planet) through which molten lava and gases erupt
the large hole at the top of a volcano formed when the roof of a volcano's magma chamber collapses
a wide, flat landform that results from repeated nonexplosive eruptions of lava that spread over a large area
an area of deep cracks that forms between two tectonic plates that are pulling away from each other
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