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What is a Volcano?
In simple terms a volcano is a mountain
that opens downward to a pool of molten
rock (magma) below the surface of the
earth. It is a hole in the Earth from which
molten rock is stored.
Eruption
An eruption simply takes place when the
magma stored in the reservoir reaches
sufficient pressure to overcome the
resistance of the rock that forms the roof of
the magma chamber.
Many things can cause this change in
pressure to occur including earthquakes,
plate movement in the Earth, melting
glaciers, changes in tide and rainfall.
Magma Chamber
A magma chamber is a large underground pool
of molten rock sitting underneath the Earth's
crust. This magma is less dense than the
surrounding mantle and so it seeps up to the
surface through cracks and flaws in the crust.
When it reaches the surface, it results in a
volcanic eruption.
Ash Cloud
Volcanic ash consists of small pieces of
compressed rock and glass created during
volcanic eruptions. These fragments are so
small, and heated to such a temperature that
they can be carried in the air for many miles.
Lava
Lava is the rock expelled from a volcano during
an eruption. When it first comes out, the lava
can have a temperature higher than 700
degrees C. It then flows downhill from the
eruption point until it cools and hardens
Main Vent
A volcano's main vent is the point in the Earth's
crust where hot magma has reached the
surface. The familiar cone-shaped volcano
builds up as ash, rock and lava ejected during
eruptions fall back to Earth around the vent
Did you know?
The name "volcano" has
its origin from the name
of Vulcan, a god of fire
in Roman mythology.