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Mount St Helens


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A volcano within the Cascade volcanic group in southern Washington State, USA, which had been dormant since 1875 but erupted violently on 18 May 1980. Before the eruption magma was pushed upwards beneath Mount St Helens, causing the mountain to bulge and the ground surface to tilt. The explosive eruption released pressure on the magma, causing a massive landslide and a powerful lateral blast which deposited ash and blew down trees over a wide area.

Subjects: Environmental Science.


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