What made Mount St. Helens explode?

rocky Reader

Hi Reader,

A sudden sliding of the north slope of the volcano caused a dramatic reduction of pressure of the underlying magma. Gas rapidly came out of the magma, which caused the eruption. (In much the same way that a can of soda will foam rapidly if you shake the can before you open it.) The 1980 eruption of Mount St. Helens was a Plinian eruption.

Sincerely,
John Dvorak 

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