The area is subjected to frequent earth movements and has a long history of volcanic activity. The mountains have formed as a result of seismic activity. The American coast is social occasion of the North American Plate; the Pacific Ocean to the western lies on the Juan de Fuca plate. The Juan de Fuca plate is subducted below the North American plate. As the subducted Juan de Fuca plate is subjected to increasing pressure it becomes hotter and begins to melt. The molten rock, called magma begins to rise towards the show up. When it reaches the surface it erupts and a volcano is formed.

Mt St Helens is incidentally an active complicated volcano as it is found on a baneful plate margin.
Like the other volcanoes found in the Cascade Range, Mt St Helens (MSH) had been dormant for many years. In March 1980 there were signs of an impending eruption, as several earthquakes occurred. However on the 18th March 1980, an earthquake measuring 5.1 on the Richter Scale rocked the volcano. at heart a few seconds of the earthquake, the volcano erupted and the whole northern location of the volcano collapsed causing the largest known landslide in US history. This pulverised rock, glacier ice and ash wiped out all alive things up to 27km north of the crater. In the blow out zone, the trees (some of which were cholecalciferol year...If you want to get a full essay, order it on our website: Ordercustompaper.com
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