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The Learning Kingdom's Cool Fact of the Day for September 24, 1999
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Why does hot lava sometimes explode?
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Volcanoes sometimes erupt in violent explosions. Other volcanoes
erupt more peacefully, but lava can still spray up in magnificent
fountains. Where does all that energy come from?
Deep in the Earth, hot magma (unerupted lava) exists under extreme
pressure. Under such high pressure, a large amount of gas can
dissolve into it. As the magma moves up toward the surface, the
pressure steadily decreases.
Under less pressure, gas cannot dissolve as much. When it comes out
of solution, the gas forms bubbles that dramatically increase the
volume of the magma, sometimes causing it to shoot up in large
fountains at the surface.
If the pressure is released suddenly (say, by a landslide) then the
lava can explode violently, releasing the gas all at once and
possibly destroying an entire mountain in one single blast.
More about volcanic gases:
http://hvo.wr.usgs.gov/volcanowatch/1996/96_08_25.html
http://volcano.und.nodak.edu/vwdocs/Gases/
Today's Cool Word names a hole that releases volcanic gases:
http://www.cool-word.com/archive/1999/09/24.html
More Cool Facts about volcanoes:
http://www.cool-fact.com/archive/1997/10/15.html
http://www.cool-fact.com/archive/1998/06/19.html
http://www.cool-fact.com/archive/1999/07/27.html
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