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Crater The usually circular large hole at the top of a volcano.
Magma The molten liquid, beneath the earths surface.
Lava The molten liquid that escapes from a volcano.
Magma Chamber A reservoir of magma beneath the earth's surface.
Vent A hole in the earth from where volcanic substances are released such as
gas, steam or lava.
Pyroclastic flow A mixture of solid, semisolid and gas that flow down the edge
of a volcano. It is very hot and fast moving often over 62 miles and hour.
Ash A finely ground lava , now powdery substance, released from a volcano
during an eruption
Tephra Fragments of volcanic matter thrown out during an eruption e.g. dust.
Volcanic Explosivity Index The scale formulated to express the severity of a
volcanic eruption .e.g. 0 non explosive , 8 mega colossal