How does the lava get out of the volcano?
Scott (Age 7)
Hi Scott,
When it is still underground, molten rock is called magma. After it has been
erupted onto the surface we call it lava. Magma has gas bubbles in it, and they
want to expand. Usually the pressure of the overlying rock layers is high
enough so that they don't expand (sort of like the cap on a soda bottle keeping
the bubbles in the soda). If the gas pressure in the magma gets too high, the
bubbles start to expand. They also want to rise, and as they rise they bring
the magma up with them. If the pressure gets too high, the volcano fractures
and the magma can escape to the surface. This allows the bubbles to expand
really quickly and you have an eruption!
This is how we think the process works. Lots of people are doing experiments
and studies to try and understand it better.
Good luck on your volcano studies.
Sincerely,
Scott Rowland, University of Hawaii
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