U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismic
Network, Seattle, Washington
CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE
Friday, May 9, 2008 12:45 PDT (Friday, May 9, 2008 19:45 UTC)
MOUNT ST. HELENS VOLCANO (CAVW#1201-05-)
46.20°N 122.18°W, Summit Elevation 8363 ft (2549 m)
Volcano Alert Level: ADVISORY
Aviation Color Code: YELLOW
SUMMARY:
The pause in lava dome growth continues, and all our monitoring instruments show trifling or nil volcanic-related activity. This pause, which began in late January 2008, was recognized by absence of measurable growth among successive fixed-camera images, nearly quiescent seismicity, and the absence of tilt signals that might characterize extrusion of lava from the conduit.
We continue to monitor closely for evidence of renewed extrusion or other activity. The new lava dome remains hot in places; thus, it is capable of producing hot avalanches or small steam explosions that could cause hazardous conditions in and around the crater. Sudden melting of snow and ice could send small lahars onto the Pumice Plain and perhaps down the Toutle River as far as the Sediment Retention Structure (SRS). Ash clouds from explosions could affect aircraft.
RECENT OBSERVATIONS:
Monitoring data from field sites showed no change during the past week--the volcano remains quiet.
The 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: http://vulcan.wr.usgs.gov/Volcanoes/MSH/Eruption04/
For seismic information: http://www.pnsn.org/HELENS/welcome.html
For a definition of alert levels: http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/volcano_warning_scheme.html
For a webcam view of the volcano: http://www.fs.fed.us/gpnf/volcanocams/msh/
Telephone recordings with the latest update on Mount St. Helens and phone contacts for additional information can be heard by calling: (360) 891-5180.
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 Seismic
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.
Past Updates
Mount St. Helens Current Eruption Menu
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