Cascade Range Current Update |
U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismic Network, Seattle, Washington Saturday, January 12, 2008 12:57 PST (Saturday, January 12, 2008 20:57 UTC) MOUNT ST. HELENS UPDATE Current Volcanic- Alert Level WATCH; 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 rising above the crater rim today would drift eastward early in the day, and shift southeastward alter in the day. 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: Poor weather precludes views of the mountain this morning. At abut 0711 and 0723 local time a pair of moderate sized, but raggedy, earthquakes occurred. Emergent, rather than sharp, onsets suggest that they could involve rockfalls, but the exact nature of these events is under review. Such events indicate that the dome is still active and growing and that the volcano remains in a state of eruption, but do indicate any significant change in eruptive activity. 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.
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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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