Q:

When did Mount Saint Helens erupt?

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Quick Answer

Mount St. Helens' most significant eruption in modern times occurred on March 20, 1980. It was followed by additional eruptions between Dec. 7, 1989 to Jan. 6, 1990, Nov. 5, 1990 to Feb. 14, 1991, Oct.11, 2004, Mar. 8, 2005, and between Jan. 16, 2008 to July 10, 2008.

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When did Mount Saint Helens erupt?
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Prior to the 1980 eruption, recorded eruptions from 19th century include a major eruption in 1800, followed by smaller eruptions between 1831 to 1857. During that time, the largest eruption occurred in 1842. Other major eruptions date to 1480, 400 B.C., 1200 B.C., 1600 B.C., 1900 B.C. and 2500 B.C. It experienced a 2,000-year eruptive period beginning 20,000 years ago and another eruptive period that ended about 35,000 years ago.

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Related Questions

  • Q:

    When is Mount St. Helens going to erupt again?

    A:

    While it is not yet possible to predict volcanic eruptions decades in advance, the U.S. Geological Survey’s Cascades Volcano Observatory continually monitors Mount St. Helens to gather data for more accurate short-term predictive models. According to “Future Eruptions at Mount St. Helens,” this volcano is the most likely to erupt in the Cascade Mountains of Washington again in the coming decades.

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  • Q:

    When did Mount St. Helens erupt?

    A:

    The largest eruption of Mount St. Helens in recent history occurred on May 18, 1980, when a cataclysmic eruption removed most of the northern face of the mountain. At 8:32 a.m. PDT, the summit collapsed into a rock debris avalanche that released a lateral gas explosion.

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  • Q:

    Why did Mount Pinatubo erupt?

    A:

    In March 1991 and April 1991, magma rising 20 miles beneath the surface of the Pinatubo volcano caused many earthquakes and small explosions, which destroyed parts of the volcano. Then on June 12, 1991, magma filled with gas reached the surface, and the volcano erupted.

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  • Q:

    What caused the 1980 Mount Saint Helens eruption?

    A:

    The catastrophic Mount Saint Helens volcanic eruption that took place on May 18, 1980 was the result of several factors that began with an accumulation of magma within the mountain's edifice earlier that year. A resulting bulge on the mountain's north flank was further weakened when an earthquake triggered a debris avalanche that relieved the pressure that had been acting as a counter-force to the magma buildup. Relieving the pressure resulted in the water that was contained within the system turning into steam, which then forced its way out explosively through a landslide scar.

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