Cascade Range Current Update

MOUNT ST. HELENS UPDATE
Saturday, January 15, 2005 11:00 a.m. PST (1900 UTC)

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, episodic changes in the level of activity can occur over days to months. The eruption could also 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 ash clouds that rise above the crater rim today would drift westward at low altitude and eastward at higher altitudes early, becoming northward at low altitude and northeastward at higher altitudes later in the day.

Recent observations: Field crews had a successful day in the field yesterday. An instrument package containing a video camera and gas sensor was installed between the new and old lava domes and will send back a scene every five minutes of the north end of the new lava dome, which is the end at which lava is actively extruding. A “spyder” containing a GPS unit and a seismometer was slung by helicopter onto the north end of the new lava dome. The spyder was visible on the video images. Both packages will aid us in closely tracking the movement and growth of the new lava dome and in better understanding seismic signals. Geologists also collected new rock and ash samples and technicians serviced one of the seismic stations on the outer flanks. The dome continues to grow and fracture. A large slab on the west side of the dome had collapsed recently and had generated a small rock avalanche and ash cloud that had drifted over the south crater rim. A bright glow on the VolcanoCam seen Thursday night was likely caused by this event.

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/News/framework.html

For seismic information: http://www.pnsn.org/HELENS/welcome.html

For a definition of alert levels: http://vulcan.wr.usgs.gov/News/framework.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:

Media (360) 891-5180

General public (360) 891-5202

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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