By: Elizabeth Hendershot MT. ST. HELENS ERUPTIO N ON MAY 18, 1980

Facts about Mt. St. Helens It’s located in Washington state. It’s a strato/Composite volcano. It’s 8,363 ft. tall. It was quiet for 123 years before 1980.

History of Mt. St. Helens It was once 9,677 ft. tall. The 9th highest peak in Washington. It formed Spirit Lake in a earlier eruption. In 1792 Captain George Vancouver of the Royal British Navy Spotted Mt. St. Helens and gave it it’s present name is considered to be the last major eruption until was the last eruption until It was small.

Volcano Surroundings It’s part of the Cascade Mt. range. The Gilford Pinchot National Forest is at it’s base. Spirit Lake is at it’s base. It was once one of the most beautiful mountain in the Cascade Range. It’s located in Washington State.

The First Signs On March 27 th the Mountain showed it’s first puff of ash. It left a 250 ft. crater. On March 30 th there were 79 earthquakes on the Mountain. On April 3 rd eruptions were almost a daily occurrence. The crater was now 1,500 ft. wide. In late April a bulge started to form 5 ft. a day.

Before the Eruption It was a beautiful quiet Sunday. Every one had been lulled into a false security, even the scientist. The Mountain had been very quiet. The people who had been evacuated were threatening to come home.

Eruption At around 8:30 Am the Volcano erupted. A wall of rock, ice, and trees was swept from the Mountain latterly at 500 miles per. Hour. A 5.1 earthquake struck 1 mile below it at the same time. A 1,300 landslide, the largest in recorded history swept the Mt. enterer north side away.

Eruption The heat instantly melted 70% of the snow and glacial ice on top of the Mt. The mass of rock, water, ice, and trees swept down the Mt. into Spirit Lake at 175 miles per. Hour. Then pyroclastic materials and the gases erupted from the volcano. It moved at 650 miles per. Hour. It flattened 230 square miles in 3 min.

Effects of the Eruption 57 people were killed. People were fond dead as far as 7 miles from the Mt. Trees 6 miles from the Mountain were uprooted. The areas near the Mountain were completely striped of top soil.

Effects of the eruption Today Spirit Lakes surface is 100 ft. above it’s original surface. Spirit Lake also has 2 ½ more surface area than it used to. After 2 weeks the pyroclastic material was 650 degrees hot.

Effects of Eruptions Some boulders from the eruption were 20 ft. in diameter. 27 bridges were destroyed Rock, ash, and even houses flouted down the Toutle River. Spirit Lake can’t sustain any life larger than a fish it’s so polluted today.

Effects of Eruption After 6 days of dredging, ships still could only go in a small section of Toutle River. There was 25 ft. wall of debris. Many animals and plants were destroyed and killed in the eruption. The ash was 60 ft. deep in the valley.

Mt. St. Helens current Status The hasn’t been any recent activity. There’s normal activity.

Strato/composite Volcano There known for the pyroclastic material when they erupt. Also there Pahoehoe Lava. (High in Viscosity).

Thank You For Listening To My Presentation!

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