Mount St. Helens

Mount St. Helens

Mount St. Helens was once considered an excellent example of a stratovolcano. This means that it was a volcano that was built up of alternate layers of lava and ash. These kinds of volcanoes are also know as composite cones and are some of the mostly deadly volcano types. Mount St. Helens was formed by the subduction of the oceanic plates. In the case of Mount St. Helens was the Juan De Fuca Plate beneath the North American plate. Mount St. Helens is known for the eruption that started on March 27, 1980. Before this eruption scientists had started to see increased earthquake activity in the area. On May 18, 1980 the volcano finally fully erupted in part to a magnitude 5.1 earthquake. On the north side of Mount St. Helens the volcano collapsed. This volcano was considered explosive. It caused a lot of damage and death. Mount St. Helens has erupted multiple times, but the last known time that it erupted was in 2008.

Hazards that were associated with this particular volcano were lava flows, explosive eruptions and large lahars. These hazards were associated with the eruption and headed down the volcano into the valley below. The ash continued in the 1980 eruption for almost a month. While this volcano was certainly not the biggest eruption, it was widely known for the way that it erupted.

Mount St Helens. (2012). Retrieved from http://www.mountsthelens.com/history-1.html