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 8, 2004, 7:00 a.m., PDT
Current status is Volcano Advisory (Alert Level 2); aviation color
code ORANGE
Seismic activity continues to be at a low to moderate rate with an
overall trend of slightly decreasing energy release over the past 24
hours. Earthquakes are occurring at a rate of 1 to 2 per minute with
the largest magnitudes about M1.5. Yesterday field crews reported
a new vent near the two that have been present for several days.
They also reported that there has not been noticeable additional
uplift of the south part of the dome and adjacent glacier in the past
24 hours. Gas-sensing and thermal imaging flights occurred late yesterday
afternoon and we are awaiting those results. There will be limited
work in the field today due to the poor weather. Field crews today
will mostly work on enhancing data links between field stations
and the Cascades Volcano Observatory. As a result of the intense unrest of the past many 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 in
the degree of unrest and perhaps an eruption could occur
suddenly or 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 during the morning will be from the south-southwest and
any ash will drift north-northeast. The National Weather Service is
forecasting a weather front that could bring more than 1 inch of
rain to the mountains. We anticipate that such intense rain could
trigger small to moderate debris flows in the crater that may flow
out onto the Pumice Plain. 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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