The 1980 Eruption of Mt. St. Helens a case study by christina nguyen

The Most Studied Volcanic Eruption in the Twentieth Century

Mt. St. Helens was a breath-taking, snow-capped volcano that was treasured for it's symmetrical 9, 760 feet of majesty and was considered "the Fuji of America." It sits in front of Spirit Lake.

Mt. St. Helens pre-eruption
Mt. Fuji in Japan

The volcano attracted many tourists to the Cascade Mountains of southwestern Washington. The Cascades include both volcanic and non-volcanic mountains, but the mountain range is part of the Ring of Fire, which is the region of the Pacific where 75 percent of the world’s active volcanoes are located, and where 90 percent of all earthquakes occur.

Mt. St. Helens is a composite volcano, a large, steep cone of alternating layers of lava, ash, and rock, and also the most active volcano in the Cascade Range.

While shield volcanoes produce thin lava and gentle eruptions, composite volcanoes often produce a pyroclastic flow—a mixture of hot steam, ash, rock and dust.

Before the deadly eruption, Mt. St. Helens had been intermittently active with minor eruptions and seismic activity, resulting in hazard warnings and an eventual evacuation of the area.

Some were reluctant to evacuate because scientists could not predict the exact day the volcano would erupt. One old man refused to leave....

1980 Timeline:

March 20: earthquakes began to occur at a rate of about 15 per hour

March 25: about 3 earthquakes per hour

March 27: U.S.G.S issued the official hazard watch

April: Volcanic tremors were detected and a bulge began to form which then began to grow five feet per day

May 18: a devastating blast, followed by a landslide and pyroclastic flow

An earthquake triggered the largest landslide in recorded history

The ash plume reached 15 miles into the atmosphere

The blast destroyed more than 200 miles of the forest

1,300 feet was blown off of the top of the volcano

A horseshoe-shaped crater replaced the symmetrical cone


500 million tons of ash fell. It was composed of particles of glass and rock, which caused major health problems, destroyed agricultural crops, and damaged mechanical and electrical equipment.

Ash removal cost 2.2 million dollars and took 10 weeks in Yakima; two people died of heart attacks from shoveling the ash.

People died from asphyxiation from inhaling the hot volcanic ash, and some died from thermal and other injuries. People who survived suffered from anxiety, post-traumatic stress disorder, and had trouble sleeping.

A total of 57 people died.

The Mt. St. Helens eruption was the most destructive in U.S history in terms of economic impact.

It cost the U.S an estimated total of 1.1 billion dollars in damage, and Congress also “approved 950 million dollars in emergency funds to the Army Corps of Engineers, FEMA, and the Small Business Administration to help recovery efforts” (Bagley, 2013).

According to Oregon State University, “Thirty logging trucks, 22 transport vehicles, and 39 railcars were damaged or destroyed along with 4.7 billion board feet of timber”.

The ice and snow on top of Mt. St. Helens melted, causing flooding, mudflows, and lahars. A lahar is a geologic term for a destructive mudflow on the slopes of a volcano.

Millions of fish died, trees were ripped out of the ground, and roads, bridges, and railways were damaged.

Flights cancelled, telephone lines and electricity were knocked out, and more than 200 homes were destroyed.

In addition to these losses, the tourism industry greatly declined, causing the local economy to lose revenue.


In 1982, Mt. St. Helens became a National Volcanic Monument as declared by Congress.

Last year, 2015, the U.S commemorated the 35-anniversary since the eruption. Today, tourism has returned in spite of, and because of the eruption; more than 300,000 people visit each year.

Mt. St. Helens is still active and will erupt again in the future. But when??

Works Cited:

Bagley, M. (2013, February, 28). Mount St. Helens Eruption: Facts & Information. retrieved

October 27 2016, from LiveScience Web Site:

Bernstein, R. S. Baxter, P, Faulk, H, Ing, R, & Foster, L (1986). Immediate Public Health Concerns

and Actions in Volcanic Eruptions: Lessons from the Mount St. Helens Eruptions, May 18-October 18, 1980. Supplement, 76. retrieved October 25 2016, from

Diggles, M. (2000, March, 15). Volcanic Ash Fall - A "Hard Rain" of Abrasive Particles. retrieved

October 25 2016, from USGS Web Site:

Coffin, H. (1983). Mount St. Helens and Spirit Lake. retrieved October 26 2016, from Geoscience

Research Institute Web Site:

Endo, E. T., Malone, S. D., Noson, L. J., & Weaver, C. S. (1980, June 19). Eruption of Mt. St.

Helens. Nature, 285, 529-531. doi:

History – Mt. St. Helens. (2012). Retrieved October 25, 2016, from

Reed, C. (2015, May 17). What have we learned in the 35 years since Mount St. Helens erupted? Retrieved October 29, 2016, from

Saarinen, T. F. Warning and Response to the Mount St. Helens Eruption. (n.d) retrieved October

26 2016, from

Turgeon, A (2015, January, 6). Ring of Fire. retrieved October 25 2016, from National

Geographic Society Web Site:

Volcanoes and Volcanic Eruptions. (2014). retrieved October 27 2016, from BBC Web Site:

What were the effects on people when Mt St Helens erupted?. (2016). retrieved October 27

2016, from OSU Web Site:


Created with images by Forest Service - Pacific Northwest - "800518-3-1 Mt St Helens Eruption 5-18-1980 - USGS" • Derek K. Miller - "Mount St. Helens 1978 - before the eruption"

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