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 ash clouds that rise above the crater rim today would drift east-southeastward early in the day. Later in the day any ash clouds would drift southward at low altitudes and southeastward at higher altitudes.
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: No significant changes in patterns of earthquakes or ground deformation have occurred over the past day. Analysis of a digital elevation model made from photographs taken on December 15, 2005, shows that the volume of the new lava dome at that time was about 73 million cubic meters (95 million cubic yards). Previously we had estimated that the new dome probably surpassed the volume of the 1980-1986 lava dome (77 million cubic meters or 100 million cubic yards) by the end of 2005. But it looks like that milestone might not have been met until recently. A model to be made from photographs taken on February 8, 2006, will tell us in a few weeks.
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:
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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