Thursday, August 10, 2006

Mount St. Helens eruption

The eruption of Mount St. Helens in 1980 is the momentous volcanic eruption to occur in the lower 48 U.S. states which has recorded a history, leading a vicious power and volume of material released by the 1915 eruption which took place in California's Lassen Peak. The eruption was preceded by a two-month-long series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the mountain which created a huge bulge and a fracture system on Mount St. Helens' North Slope. The entire weakened north face to slide away suddenly exposes the partly molten, gas- and steam-rich rock in the volcano to lower pressure due to the earthquake which caused at 8:32 AM on May 18, 1980.


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