Monitoring Mount Rainier
The last significant eruptive activity at Mount Rainier
was between 120 and 160
years ago, and several minor eruptions were reported during the late 1800's.
A careful stratigraphic study of the volcano's recent products led
scientists to conclude that "Mount Rainier will almost surely erupt again
sometime within the next few hundred years," and that future eruptions might
endanger the livelihood of thousands of people. Hence, the need for
careful monitoring
of this loftiest peak in the Cascade Range.
-- Dzurisin, et.al., 1983
In response to
renewed eruptive activity at Mount St. Helens in 1980,
the
Cascades Volcano Observatory (CVO) was established
in Vancouver, Washington,
with the support of the
U.S. Geological Survey's Volcano Hazards Program.
-- Chadwick, Iwatsubo, Swanson, and Ewert, 1985
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Earthquake Monitoring
Earthquakes commonly provide the earliest warning of volcanic unrest, and
earthquake swarms immediately precede most volcanic eruptions.
Information on Pacific Northwest
earthquake activity and hazards
is provided by
the
Pacific Northwest Seismograph Network (PNSN)
which operates seismograph stations and locates earthquakes
in Washington and Oregon. The PNSN
is operated jointly by the University of Washington, the University of Oregon,
and Oregon State University, and is funded by the U.S. Geological Survey, the
Department of Energy, and the State of Washington. The PNSN
is based at the Geophysics Program of the University of Washington in Seattle,
and is a member of the Council of the National Seismic Systems (CNSS), a group
of regional network operators who cooperate to locate and catalog earthquakes
throughout the United States.
-- Wright and Pierson, 1992; and
the University of Washington's Geophysics Program
[Map,13K,InlineGIF]
University of Washington's Pacific Northwest Seismograph Network - Mount Rainier
Vicinity, 1997.
-- Modified from: University of Washington Geophysics Program
Link to:
Current Seismicity
-- Link courtesy University of Washington Geophysics Program
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Geochemical and Geodetic Studies
In addition to continued
monitoring at Mount St. Helens,
CVO scientists have
initiated geodetic and geochemical monitoring at other potentially active
volcanoes in the Cascade Range.
Geochemical studies include temperature
measurements and gas sampling of
fumaroles, while
geodetic studies
consist of: (1)
slope distance and vertical angle measurements,
(2)
tilt surveys,
and
(3)
precision gravity surveys.
CVO Deformation Project -
Volcano Networks
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EDM |
GPS |
Leveling |
Tilt Meter |
Dry Tilt |
MAG |
Mount Rainier, Washington |
1982
1983
1988
1989
1994 |
1994 |
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1982
1983
1988 |
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These
networks,
once the baseline information has been collected, can detect
surface deformation that may reflect magma movement up the conduit. The rates
of deformation increase as magma approaches the surface, and these measurements
can therefore help determine where and when an eruption may occur.
-- Chadwick, Iwatsubo, Swanson, and Ewert, 1985; and
Iwatsubo and Swanson, 1992
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