International Glaciospeleological Survey
Mount St. Helens
Kendall Heskett
Famous for its symmetrical cone, Mount St. Helens was thought of as the “Fuji of America.” Commander George Vancouver and the officers of the H.M.S Discovery named it after the British diplomat Alleyne Fitzherbert whose title was Baron St. Helens. They came across the volcano while surveying the northern Pacific coast between the years 1792 and 1794. Mount St. Helens is located in the southwestern part of Washington, approximately ninety-five miles from Seattle. Part of the Cascade Mountain range (which stretches seven hundred miles from British Columbia to Northern California), Mount St. Helens -- like a majority of the other peaks in the Cascade Range -- is a volcano. For the past 4,500 years Mount St. Helens has been the most active and most explosive volcano in the Cascade Mountain range. It has erupted regularly every couple of hundred years. The 1980 eruption of Mount St. Helens was the first to occur in the continental United States since 1917. Mount St. Helens had been rather quiet for 123 years. During the 1800s there were a few small eruptions. After the year 1857 the mountain was very quiet. Over the ensuing years, it became a popular vacation spot. One of the most heavily visited sites was Spirit Lake, which was located at the base of the volcano. Many activities such as camping and boating took place there. In 1978 two geologists, Dwight Crandell and Donal Mullineaux from the U.S Geological Survey studied Mount St. Helens and predicted that the volcano could erupt before the year 2000. The first event signaling Mount St. Helens’ reawakening occurred on March 27, 1980 at 12:30 pm. This was an earthquake that measured 4.2 on the Richter scale. The top of the mountain ruptured, steam and ash were ejected, and a crater formed in the glacial ice cap. A second crater was created on March 29, 1980. By April 7, 1980 the two craters had joined together to make one large crater. The crater eventually grew to more than 1,700 feet across and 500 feet deep. Ominously, within a couple of weeks an area one mile long and a half mile wide expanded outward 450 feet from the volcano's side. This area was named the “bulge.” It was caused by a rise in molten rock into the volcano.
Above is a picture of one of the seismograph
readings collected the week preceding the eruption.
Due to this observation, the governor of Washington took it upon himself to declare a state of emergency and recommended that people evacuate. From that day in April to May 17, 1980 only a few small eruptions occurred. However, there were still high readings that the seismologists were concerned about. On the morning of May 18, 1980 at 8:32 am the event the seismologists were expecting arrived. After almost two months and thousands of small earthquakes, an quake measuring 5.1 on the Richter scale caused Mount St. Helens to collapse. A massive landslide of snow, rock, and ice spilled from the north side of the volcano at a speed of about 200 miles per hour. It was the largest landslide in recorded history. Before the eruption the volcano was 9,677 feet tall. After the eruption it was 8,363 feet tall. Therefore, the volcano lost 1,314 feet that day. The landslide exposed magma and gases and produced an explosive eruption that reached 80,000 feet in 15 minutes. At the same time, a pyroclastic flow reaching 600 degrees Fahrenheit blasted forward at more than 300 miles per hour. This blast killed fifty-seven people. It eliminated large populations of elk, bear, deer and coyote. It destroyed river valleys and enough trees to build 300,000 houses. The melted glaciers mixed with ash to generate a lahar that washed away buildings, bridges and roads. A thick layer of volcanic ash was spread over a wide area of central Washington. It caused complete darkness 250 miles away from the volcano.
Mount St. Helens after the eruption
Map of areas affected by the eruption
Landsat satellite images made in 1980 before (l) and after (r) the eruption.
The red areas show green, living vegetation. It is evident that much of the
vegetation north of the volcano was wiped out by the pyroclastic flows
Since 1980, numerous smll eruptions have built a mound of lava called a lava dome. The dome is 3,450 feet wide and rises more than 1,000 feet from the crater’s floor. However, the dome has only replenished about four percent of the mass of the volcano that was sheared off in the May 1980 eruption. Scientists estimate that it would take about twenty-five such lava domes to rebuild the volcano to its pre-1980 dimentions.
Two views of the lava dome of Mount St. Helens
One man’s refusal to evacuate the area made him famous: Harry R. Truman, who had a lodge on Spirit Lake at the base of Mount St. Helens. Truman had managed his lodge on Spirit Lake for fifty years and refused to abandon his life’s accomplishments. When Mount St. Helens erupted on May 18, 1980, Truman’s lodge was in the direct path of the explosion. Thus, Harry was killed. An estimate was made that the thickest part of all of the debris from the explosion was about one and a half miles to the west of Truman’s Spirit Lodge. Therefore, Truman is most likely buried under a large mass of volcanic debris. This event made Harry R. Truman a famous man. After his refusal to evacuate, reporters from all over the country came to interview him. After he was declared dead, various books, songs and even one movie written about his life.
