Cascade Range Current Update

MOUNT ST. HELENS UPDATE
Wednesday, January 26, 2005 10:15 a.m. PST (1815 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 west-northwestward to northward.

Recent observations: The volcano is obscured by clouds this morning. Although conditions for the gas-sensing flight on Monday were poor, analysis of data suggests that the emission of sulfur dioxide is about the same as in previous measurements (range of 50 to 250 tons per day). At yesterday’s press briefing there was a lot of interest in gaining better perspective about the size of the uplifted welt and new lava dome. The total volume change represented by the welt and dome as of 3 January of this year is 34 million cubic meters (or 44 million cubic yards). For Portlanders, that is equivalent to 134 Rose Garden arenas. The area of the dome and uplift covers about 60 city blocks. In Portland an equivalent area would extend from the Morrison Bridge to the Hawthorne Bridge and from the Willamette River to the Park Blocks. The top of the new lava dome rises about 550 feet above the pre-eruption surface of the flanking glacier. But the lava dome probably extends to the base of the glacier, which means that its true height is closer to 1100 feet.

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.

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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