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 10, 2004, 5:00 p.m, PDT Current status is Volcano Advisory (Alert Level 2); aviation color code ORANGE Seismic activity remained at a low level today. Currently small earthquakes (about magnitude 1) are occurring at a rate of about 1 per 5 to 10 minutes. Very small earthquakes are occurring at a rate of about 1 per minute. Visual observations and thermal imaging of the crater, the 1980-86 lava dome, and the intensely deforming and uplifting area on the south side of the dome were made during the early afternoon. The deforming area has increased in area by about 10 percent since last seen on 7 October. Estimate of change in height awaits further analysis. A steam plume originating at vents on the deforming area is rising above the crater rim and drifting to the southeast. A dusting of ash on new snow high on the volcano suggests that minor ash emission may be occurring intermittently. Installation of a remotely controlled video camera provided by the USGS Hawaiian Volcano Observatory began late in the day at Sugar Bowl, which lies at the eastern side of The Breach, the open north end of the 1980 Crater. 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 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 winds early this evening will remain northwesterly. Any ash clouds will drift south-southeastwardly to southeastwardly. Tomorrow’s media briefing will be held at the Headquarters of the Gifford Pinchot National Forest at 10:30 a.m. |
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