Cascade Range Current Update |
U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington
Volcanoes in the Cascade Range are all at normal levels of
background seismicity except for Mount St. Helens. See Mount St.
Helens update below.
Other volcanoes include Mount Baker, Glacier Peak, Mount
Rainier, and Mount Adams in Washington State; Mount Hood,
Mount Jefferson, Three Sisters, Newberry, and Crater Lake, in
Oregon; and Medicine Lake, Mount Shasta, and Lassen Peak in
northern California.
USGS Cascades Volcano Observatory, the Pacific Northwest
Seismograph Network at the University of Washington, and the
USGS Northern California Seismic Network and Volcano Hazards
Team in Menlo Park, California, monitor the major volcanoes in the
Cascade Range of northern California, Oregon, and Washington.
Mount St. Helens Update, October 7, 2004, 6:50 a.m, PDT
Current status is Volcano Advisory (Alert Level 2); aviation color
code ORANGE
The low rate of seismic activity of the past day increased slightly
overnight. Earthquakes are presently occurring at a rate of about 1
to 1.5 per minute with maximum magnitudes of about 1.0. Late
yesterday afternoon scientists were able to get brief views of the
vents and the area of intense uplift on the south side of the 1980-
86 lava dome. They saw only weak puffs of steam coming from
vents. They were able to confirm that the top of the area of intense
uplift is at or slightly above the highest point on the lava dome,
which suggests that some uplift has occurred during this period of
low seismicity. They were also able to observe areas affected by
the small lahars that spilled out of the crater and onto the Pumice
Plain during the rainstorm in the early morning of 6 October.
Lahars flowed a short distance toward both Spirit Lake and the
North Fork Toutle River. Today, field crews will continue to harden GPS sites for the
approaching winter, do a gas-sensing flight, take thermal images
of the dome and crater floor and make geological observations. As a result of the intense unrest of the past 11 days, we infer that
magma is at a very shallow level. During times of unrest, Mount St.
Helens and similar volcanoes elsewhere typically go through
episodic changes in level of unrest over periods of days to weeks,
or even months. Such changes are in part driven by variations in
the rate of magma movement. We expect fluctuations in the level
of unrest to continue during coming days. Escalation of unrest
could occur suddenly and perhaps lead to an eruption with very
little warning. There may be little time to raise the alert level before
a hazardous event occurs. Therefore, we continue to monitor the
situation closely and will issue additional updates and changes in
alert level as warranted. Wind forecasts from the National Oceanic and Atmospheric
Administration (NOAA), combined with eruption models, show that
winds this morning are southwesterly and any ash will drift to the
northeast. Press conferences will continue to be held at the Headquarters
office of the Gifford Pinchot National Forest. The morning press
conference is at 9:30 AM.
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