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During the years prior to 1980 Mount St. Helens and the Spirit Lake Basin provided a recreational haven. The US Forest Service estimated that over half a million people visited the Spirit Lake area in 1979. The heaviest visitation was during the summer months, when most came to camp, hike and fish. Camps belonging to the Boy Scouts, Girl Scouts and YMCA were located along the northeast arm of Spirit Lake. Other private lodges and cabins dotted the lakeshore and along State Route 504 for several miles to the west. Few of these thousands of visitors realized that this recreational paradise contained an active volcano. |
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Mount St. Helens began to show the first signs of volcanic unrest in March of 1980. Earthquakes, ground deformation, and steam explosions would continue for nearly two months before culminating in a major eruption on May 18. The purpose of this portion of our website is to provide a summary of the events that led to this eruption. To Continue - There are two ways to access this portion of our website. You may Start at the first week (March 15-21, 1980) OR click on a specific date on the calendar below and to the right to see what was happening on that day in 1980. |
 Map of Mount St. Helens area and the Spirit Lake basin prior to the 1980 eruption. Key landmarks are noted and referred to in later sections of the site. |
Start at the week beginning March 15 or choose a date from the 1980 calendar below |
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Mount St. Helens' sunset before 1980. The peak's symmetric cone earned
it the title of the "Fuji of North America." USFS photo courtesy of Jim Hughes.
Although historical accounts of eruptions during the 1800's suggested
the possibility of renewed volcanic activity at Mount St. Helens, the foundation
of scientific information that allowed realistic evaluation of the hazards was laid
over several decades. Because the mountain has long been a favorite of climbers and
naturalists, two areas of fumaroles and warm ground had been documented as early as 1939.
The first systematic geologic investigation was a reconnaissance study begun in the
1930's by Verhoogen. According to his report published in 1937, "activity of the volcano
seems to have continued without interruption until very recent times. Many [lava]
flows cannot be more than a few hundred years old, as evidenced by the vegetation."
Later geologic studies verified the relative youth of volcanic deposits from
Mount St. Helens. The geologic record of past eruptions was sufficiently well documented
by 1975 to enable USGS geologists Dwight Crandell and Donal Mullineaux and geochemist
Meyer Rubin to warn, in an article in Science magazine, that "...an eruption
is likely within the next hundred years, possibly before the end of this century."
Crandell and Mullineaux produced a more comprehensive assessment of the
volcanic hazards at Mount St. Helens in 1978 as part of a broad USGS program for the
systematic evaluation of volcanic hazards in the Cascades. The results were published as
USGS Bulletin 1383-C (shown at left). It summarized the mountain's eruptive history
over the past 4,500 years and showed hazard zones for various types of future
ashfalls, lava flows, pyroclastic flows, mudflows and floods.
The report also described Mount St. Helens as "more active and more explosive during
the last 4,500 years than any other volcano in the conterminous United States."
This report and a letter discussing its implications were sent to appropriate
Federal, State, and selected county and local agencies in southwestern Washington.
In January 1979 USGS scientists met with key Federal and State officials to explain
the implications of the report.
While the assessment of volcanic hazards was being prepared, the volcano was already
being monitored to detect early signs of an impending eruption. No one knew what
types of monitoring techniques would prove most reliable, however, because knowledge
about the behavior of Cascade volcanoes in general was limited and because Mount St.
Helens had not been active recently. University and USGS studies in the 1970's had
monitored the volcano intermittently using three approaches: (1) seismometers
that could detect earthquakes caused by the movement of molten rock, (2) precise
ground-surface measurements that could detect swelling of the volcano, and (3)
aerial infrared surveys and surface temperature measurements of the two "hot spots"
high on the mountain to detect any changes in heat emission. The volcano was also
photographed routinely from the air to detect changes in snow and ice as part of
a USGS glaciology research project. At the beginning of March 1980 the only
instrument directly monitoring Mount St. Helens was a seismometer on the
western flank of the volcano. This station (SHW) automatically transmitted
earthquake data by radio (telemetered) to seismic recorders at the University
of Washington in Seattle. Station SHW was one of about one hundred seismometers
deployed in a network throughout western and central Washington by the University's
Geophysics Program in cooperation with the USGS.