#61 - The Eruption of Mt. St. Helens 🌋

May 18th of this year was the 45th anniversary of a big event in southwestern Washington state.  This huge geological event happened on May 18th 1980. It reshaped a mountain and the area surrounding that mountain. 

We are talking about the eruption of Mt. St. Helens.  We mentioned Mt. St. Helens in podcast # 38 - “Mt Rainier and the Cascade Mountain Range”. Mt. St. Helens, like Mt. Rainier, is one of the mountains in the “Cascade Volcanic Arc." The Cascade Volcanic Arc is a chain of volcanoes that extends over 700 miles from Western British Columbia in Canada to northern California. There are several major volcanoes in that chain. One of those volcanoes is Mt. Rainier, which last erupted s about 500 years ago.  Geologists say that it will erupt again sometime in the future.

Mt. St. Helens is the volcano in the Cascade Arc that last erupted.  Geologists and volcanologists (scientists who study volcanoes) knew that something was happening  - that “something was  up” -  with the mountain starting in March of 1980. They observed some small earthquakes and volcanic eruptions and they were watching the mountain carefully during March and April.

They were worried because they noticed that the activity was increasing. On April 30 the governor of Washington created a “red zone” around the volcano. No one was allowed to enter this zone. The last week of April 1980 geologists noticed a bulge on the north side of the mountain. A bulge is a swelling on the surface of something – when the surface sticks out or projects.

The scientists watched this bulge grow bigger every day; more earthquakes occurred below this bulge. At 8:32 on May 18 it happened! There was an earthquake on the north slope or incline of the mountain followed by a volcanic blast or explosion.

There was a plume of ash 80,000 feet in the sky. A plume is a feather of a bird, but we also use “plume” to describe something that is the shape of a feather – long and narrow. 

This plume of ash from the eruption of Mt. St. Helens reached 11 states and some Canadian provinces. There was also a big landslide. The north side of the mountain slid away. (slide – present; slid -past). Volcanic mudflows called lahars, made of melted snow and ice mixed with the rocks and ash from the eruption, flowed down the Toutle and Cowlitz Rivers, rivers that flow down from the mountain. Unfortunately, 57 people lost their lives in the eruption. One man who died was a volcanologist who was observing the mountain, another was a photographer who had been taking pictures of the activity on the mountain.

An 83-year-old man named Harry Truman had a lodge on Spirit Lake at the base of the mountain. He lived there with his 32 cats!  State officials ordered everyone to leave the area where he lived, but Harry refused. He said, “If the mountain goes, I’m going with it.” And he died in the eruption. Most of the other people who were killed were outside the area that officials thought was dangerous.

In addition to the loss of life, the eruption killed thousands of animals, caused damage to homes, bridges and roads and destroyed 200 square miles of forest. The eruption blew the top off the mountain and left a 1 mile wide horseshoe shaped crater (round bowl shaped depression). The eruption of Mt. St. Helens is considered the most disastrous volcanic eruption in US history. 

Today Mt. St. Helens is in a quiet “dormant” or sleeping state, Scientists still watch it closely for signs of activity. Plants and animals have returned. There are visitor centers, exhibits, trails. The area is now the Mt. St. Helens National Volcanic Monument. 

Check out the Mt. St. Helens website for more information.

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