Mount Saint Helens, located in the Pacific Northwest in southwestern Washington, stood approximately 9,500 feet above sea level prior to its eruption in 1980 (Tarbuck, 2012). Part of the Cascade Mountain Range, it is a composite volcano constructed of alternating layers of lava flows, ash, and other volcanic debris with steep, symmetrical sides . It also belongs to the North American segment of the Pacific “Ring of Fire.” This is where the tectonic plate from the Pacific is forced under the North America plate. According to an article in the Associated Press, “this Cascade "subduction zone" also is the area that can produce magnitude-9 earthquakes when the plates slip or break. The magma from this zone makes its way to the surface in Northwest volcanoes” (Esser, 2012). Although the Indians called it “Louwala-Clough,” or “Smoking Mountain,” it was given its current name in 1792 by British Royal Navy Captain, George Vancouver, in honor of Alleyne Fitzherbert, who was titled Baron St. Helens (History - Mt. St. Helens, 2014).
After approximately 123 years of lying dormant, several small earthquakes were recorded in Mid-March of 1980. These small quakes were followed by an earthquake with a magnitude of 4.2 (Richter scale) on March 20, at 3:47 p.m. PST (History - Mt. St. Helens, 2014). Multiple quakes were recorded in the days that followed causing small avalanches of ice and snow. However, the mountain showed no signs of eruption. It is unclear if it was one explosion or two nearly coinciding ones that were heard throughout the region at approximately 12:36 p.m. PST on March 27th. At that time, the mountain began to emit steam and ash into the air. These initial explosions created a 250-foot-wide crater within the larger established snow and ice filled peak crater. Scientists at the Mount Saint Helens site monitored earthquakes, tremors, and ash plumes and interpreted it to mean that magma and associated gases “were on the move within the volcano,” (History - Mt. St. Helens, 2014) and there was a great chance that there would be a magma eruption.
This observable activity stopped briefly in late April and early May. On May 7th, a blasts of steam erupted sporadically over the course of several days. This activity also stopped by May 16th. A large “bulge” on the north face of the mountain had been growing since the initial eruptions. This bulge was made by the magma under the mountain. Over 10,000 quakes were recorded in a small area less than 1.6 miles directly beneath this bulge on the north side of the mountain. (History - Mt. St. Helens, 2014) The constant quakes and magma build up had been wedging the volcano apart, creating instability on the mountainside.
On May 18, 1980, a disastrous eruption occurred that would change the face of the mountain and the surrounding areas. The huge bulge suddenly collapsed, as noted by geologists Keith and Dorothy Stoffel, who witnessed the chain of events from a plane at the volcano’s summit. ...