Add Yahoo as a preferred source to see more of our stories on Google. Image of active volcano shows magma pressure inside volcanoes can destabilize slopes and trigger collapse. (CREDIT: YouTube / CC ...
One of the most explosive volcanoes in U.S. history began its eruption with a trickle, not a blast. Mount St. Helens' gas-laden magma oozed into the cone before the mountain finally erupted in 1980.
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