Interesting Facts About Mount St Helens

  • 01 of 05

    An Introduction to Mount St. Helens

    Mount St. Helens - Three Decades After the 1980 Eruption
    Angela M. Brown 2009

    Mount St. Helens is one of the Pacific Northwest's many volcanic peaks. Part of what is known as the Pacific Rim of Fire, Mount St. Helens is famous because of its recent and continuing activity. Mount St. Helens among the Cascade Mountain Range in the state of Washington, about midway between Seattle and Portland.

    The mountain itself, along with the surrounding blast zone, has been preserved as Mount St. Helens National Volcanic Monument. The landscape within the monument is being allowed to take its own course to recovery, creating a fascinating learning experience for both scientists and the public. Visitors to Mount St. Helens National Volcanic Monument will find several interesting visitor centers and a multitude of amazing views.

    About the 1980 Eruption of Mount St. Helens: Sequence of Events

    About the 1980 Eruption of Mount St. Helens: Impacts

    Recent Mount St. Helens Activity

    Mount St. Helens  Activity Through History

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  • 02 of 05

    About the 1980 Eruption of Mount St. Helens: Sequence of Events

    May 18, 1980 Eruption of Mount St. Helens

    Mount St. Helens erupted at 8:32 a.m. PST on May 18, 1980, reminding Pacific Northwest residents and people around the world of the powerful and uncontrollable forces of nature. Physical effects of the eruption were experienced in dozens of U.S. states, with ash falling as far away as Oklahoma. Visit Mount St. Helens yourself to learn more about the volcano's history and current condition.

    The sequence of events that occurred during the May 18 eruption of Mount St. Helens:

    • A 5.1-magnitude earthquake
    • The bulge and surrounding area on the north face of the volcano slid away, resulting in a huge avalanche of rocks, mud, and debris the filled 24 square miles of valley
    • The resulting release of pressure from within the volcano released a plume of ash and pumice

    The sequence of events leading up to the eruption: March - May, 1980

    It all started on March 15, 1980, when Mount St. Helens began a period of low-level seismic activity. As the activity escalated, the volcano kept us all on the edge of our seats. Here are the highlights from the events leading up to the major May 18 eruption, in reverse chronological order.

    May 17, 1980
    Law enforcement officials escorted about 50 carloads of property owners into the Red Zone to retrieve possessions.

    May 7-13, 1980
    Small explosions of steam and ash are emitted from the volcano. Intermittent earthquakes up to magnitude 4.9.

    April 29, 1980
    State officials asked the governor to close a large area around the volcano. The plan called for a Red Zone (no public access) and a Blue Zone (restricted access). Emergency services officials are frustrated because the public appeared to remain unaware of the danger.

    March 27 to April 18, 1980
    Earthquakes and steam-driven explosions occur off and on during this period.

    March 20, 1980
    A magnitude 4.1 earthquake, unlike any that had been previously detected in the area, occurred just northwest of the summit of Mount St. Helens. Seismologists were uncertain as to whether or not these first earthquakes were related to volcanic activity. They decided to deploy additional seismometers in order to better monitor future activity.

    March 15-19, 1980
    A number of very small earthquakes are recorded, but are not recognized as immediate precursors to possible volcanic activity.

    Data Source: USGS/Cascades Volcano Observatory. Check out this web site for a much more detailed chronology.

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  • 03 of 05

    About the 1980 Eruption of Mount St. Helens: Impacts

    Miles of Forests Destroyed by Mount St Helens Eruption
    Getty Images/ © Roger Ressmeyer/Corbis/VCG

    The impacts of the 1980 eruption of Mount St. Helens included:

    • Mount St. Helens was reduced by over 1,300 feet in height
    • Volcanic ash fell as far as 930 miles away
    • The debris avalanche and mudflows buried the Toutle valley to a depth of almost 50 meters
    • The eruption lasted for 9 hours
    • 57 people lost their lives, or are still considered missing
    • 250 square miles of land was damaged
    • "Countless" animals were killed - estimates are 7,000 big game animals and millions of birds, fish, and small mammals
    • Minor eruptions continued into 1986

    Facts and figures obtained from USGS summary

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  • 04 of 05

    Recent Mount St. Helens Activity

    Mount St. Helens National Volcanic Monument
    Getty Images

    Just when we start to think Mount St. Helens is settling down, the volcano vents or rumbles. Here is a timeline of recent Mount St. Helens activity.

    2005 to present
    Mount St. Helens continues to experience low rates of seismicity, low emissions of steam and volcanic gases, minor production of ash, and the growth of a new lava dome inside the crater.

    March 8, 2005
    The Mount St. Helens volcano experienced a small explosive event, with the resulting steam-and-ash plume reaching an altitude of approximately 36,000 feet above sea level.

    January 16, 2005
    Explosive eruption that scattered ash and rocks as large as 1 meter in the crater and ash eastward onto the volcano's east side.

    October 11, 2004 to present
    A new and distinctive lava dome became evident; it continues to grow and change.

    October 5, 2004
    The most vigorous steam-and-ash eruption since the start of unrest. It lasted over one hour. The ash rose to about 3,700 m (12,000 ft) and drifted north-northeastward. A light ash dusting fell in the towns of Morton, Randle, and Packwood, about 50 km (30 mi) away. A light dusting affected the east side of Mount Rainier National Park, 110 km (70 mi) north-northeast.

    October 1, 2004
    A small steam eruption, with minor ash, issued from a vent just south of the 1980-86 lava dome

    September 23-25, 2004
    A swarm of small, shallow earthquakes (smaller than magnitude 1) began on morning of September 23, peaked in midday on September 24, then declined through the afternoon of September 25.

    Data Source: USGS/Cascades Volcano Observatory

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  • 05 of 05

    Mount St. Helens Activity Through History

    Spirit Lake and Mount St. Helens Before 1980 Eruption
    Getty Images/Harald Sund

    As mountains go, Mount St. Helens is young. The volcano's oldest known deposits were erupted about 50-40 thousand years ago, and the cone that partly collapsed in 1980 is only 2200 years old. Some Indians of the Pacific Northwest variously called Mount St. Helens "Louwala-Clough," or "smoking mountain." The modern name, Mount St. Helens, was given to the volcanic peak in 1792 by Captain George Vancouver of the British Royal Navy, a seafarer and explorer. He named it in honor of a fellow countryman, Alleyne Fitzherbert, who held the title Baron St. Helens and who was at the time the British Ambassador to Spain. Vancouver also named three other volcanoes in the Cascades--Mounts Baker, Hood, and Rainier--for British naval officers.

    Here are the highlights of Mount St. Helens activity over the last 2000 years:

    Goat Rocks Eruptive Period

    Approximately 1800 A.D.
    This eruptive period lasted for 100-150 years. Known events include ash explosions in 1842, which was followed by the extrusion of the Goat Rocks dome. Contemporary accounts indicate activity several times during the 1840s and 1850s, but are non-specific and even contradictory. The last significant activity before 1980 was "dense smoke and fire" in 1857, although minor, unconfirmed eruptions were reported in 1898, 1903, and 1921

    Kalama Eruptive Period

    1479 to 1482 A.D.
    This eruptive period included two major ejections of ash, as well as lava flows and dome building.

    Sugar Bowl Eruptive Period

    Approximately 800 A.D.
    Mount St. Helens was reshaped by a combination of dome building, a lateral blast, and pyroclastic flows during this period of volcanic activity.

    Castle Creek Eruptive Period

    200 B.C. to 300 A.D.
    Major activity during this era included ejextions of ash, pyroclastic flows, and lava flows.

    Data Source: USGS/Cascades Volcano Observatory: Mount St. Helens Eruptive History