Cascade Range Current Update |
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U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington
MOUNT ST. HELENS UPDATE
Current status is Volcano Advisory (Alert Level 2); aviation
color code ORANGE: Growth of the new lava dome inside the
crater of Mount St. Helens continues, accompanied by low rates of
seismicity, low emissions of steam and volcanic gases, and minor
production of ash. During such eruptions, changes in the level of
activity can occur over days to months. The eruption could intensify
suddenly or with little warning and produce explosions that cause
hazardous conditions within several miles of the crater and farther
downwind. Small lahars could suddenly descend the Toutle River
if triggered by heavy rain or by interaction of hot rocks with snow
and ice. These lahars pose a negligible hazard below the
Sediment Retention Structure (SRS) but could pose a hazard
along the river channel upstream.
Potential ash hazards: Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), coupled with eruption models, show that any ash clouds that rise above the crater rim today would drift south-southeastward early in the day and southeastward later.
Potential ash hazards to aviation: Under current eruptive
conditions, small, short-lived explosions may produce ash clouds
that exceed 30,000 feet in altitude. Ash from such events can
travel 100 miles or more downwind.
Recent observations: Once the lowland clouds dissipate, we may be able to see a vapor plume drifting southeastward over the crater rim. The level of eruptive activity remains unchanged from that of recent weeks. A reanalysis of late September repeat photographs of the active part of the new lava dome indicates that points on the dome are moving northwestward and upward at about 5.5 meters (18 feet) per day as extrusion continues.
U.S. Geological Survey and the University of Washington continue
to monitor the situation closely and will issue additional updates
and changes in alert level as warranted.
For additional information, background, images, and other
graphics:
For seismic information:
For a definition of alert levels:
For a webcam view of the volcano:
Telephone recordings with the latest update on Mount St. Helens
and phone contacts for additional information can be heard by
calling:
OTHER CASCADE VOLCANOES
All other volcanoes in the Cascade Range are all at normal levels
of background seismicity. These 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.
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Link to:
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[University of Washington's Pacific Northwest Earthquake Information (current seismicity)]
