Definition of a Volcano
A volcano can best be described as a fissure in the earth's crust. This fissure is filled with gases and molten lava (rock). The volcano is the opening through which these gases and lava erupt. Three main factors cause the eruption of a volcano.
First Factor
The first factor in an eruption is the buoyancy of the lava. When the rocks melt into lava form, the mass of the molten rock stays the same, but the volume increases by a great deal. This is lava, which is more buoyant than the rock and rises toward the top of the volcano.
Second Factor
Gases within the magma is the second factor. The lava gives off high pressure gases like carbon dioxide and sulphur dioxide. As these gases expand, the lava is pushed toward the top. Increased pressure from the gases pushes the magma even higher, causing and eruption.
Third Factor
An eruption can also be caused by the flow of new magma into an already magma filled volcano. As the new magma enters, pressure is increased, causing the volcano to erupt. Naturally, all these forces happen rapidly with explosive pressures, causing the gases and magma to be thrown for miles around.
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