Mount St Helens

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Mount St. Helens is a volcanic mountain in the Cascade Range in North America, in the state of Washington. It is, perhaps, the most famous mountain in the range, and certainly is the most active volcano in the area today. In fact, it has probably been the most active of the Cascade volcanoes for over 4000 years. On May 18th, 1980, the mountain erupted. Becoming one the largest volcanic eruptions in U.S history. The devastation caused by the volcano was wide spread. Many plants, countless numbers of animals and insects were killed, along with 57 people who were miners, scientists, and one journalist. In addition to this, further damage to human settlements and facilities occurred. 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 part of the North American Plate; the Pacific Ocean to the west 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 surface. When it reaches the surface it erupts and a volcano is formed. Mt St Helens is incidentally an active composite volcano as it is found on a destructive 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. Within a few seconds of the earthquake, the volcano erupted and the whole northern side of the volcano collapsed causing the largest known landslide in US history. This pulverised rock, glacier ice and ash wiped out all living

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