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   1980 eruption of Mount St. Helens

   The 1980 eruption of Mount St. Helens, a volcano located in Washington state, in the United States, was a major volcanic eruption. The eruption was the most significant to occur in the contiguous 48 U.S. states (VEI = 5, 0.3 cu mi, 1.2 km3 of material erupted), in terms of power and volume of material released, since the 1915 eruption of California's Lassen Peak.
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   Mount St. Helens

   During the lead-up to the 1980 eruption of Mount St. Helens, 83-year-old Harry R. Truman, who had lived near the mountain for 54 years, became famous when he decided not to evacuate before the impending eruption, despite repeated pleas by local authorities.
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   Cascade Volcanoes

   It is estimated to have been 42 times larger than the 1980 eruption of Mount St. Helens.
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   Pacific Ring of Fire

   It was similar the 1980 eruption of Mount St. Helens, sending an ash column approximately 20 km high into the stratosphere.
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   Columbia River

   The 1980 eruption of Mount St. Helens caused mudslides in the area, which reduced the Columbia's depth by 25 feet (7.6 m) for a 4-mile (6.4 km) stretch, disrupting Portland's economy.
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   2004 and later volcanic activity of Mount St. Helens

   The new dome did not rise above the caldera created by the 1980 eruption of Mount St. Helens.
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   Cascade Range

   Mount St. Helens National Volcanic Monument was formed following the 1980 eruption of Mount St. Helens in order to preserve the devastated area and give scientists a chance to study its recovery.
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   Crater Glacier

   True to its name, the glacier lies inside the north-facing crater left by the 1980 eruption of Mount St. Helens.
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   Mount Cayley

   This volcanic eruption was similar in size to the 1980 eruption of Mount St. Helens and is Canada's most recent major eruption.
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    Mount Pinatubo

    In all, the eruption ejected about ten cubic kilometres (2.5 mile³) of material, making it the largest eruption since that of Novarupta in 1912 and some ten times larger than the 1980 eruption of Mount St. Helens.

Explore the following pages on Powerset:

• 1980 eruption of Mount St. Helens,
• Mount St. Helens,
• Cascade Volcanoes,
• Pacific Ring of Fire,
• Columbia River,
• 2004 and later volcanic activity of Mount St. Helens,
• Cascade Range,
• Crater Glacier,
• Mount Cayley,
• Mount Pinatubo