********************************** U.S. Geological Survey, Vancouver, Washington University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington ********************************** Sunday, October 8, 2006 10:57 PDT (Sunday, October 8, 2006 17:57 UTC) MOUNT ST. HELENS UPDATE Current Volcano 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 southeast. 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: Mount St. Helens is hidden by clouds this morning. Weather forecasts for Columbus Day indicate sunny weather and excellent opportunities to view the crater. Data from deformation-monitoring instruments located on the 1980-86 and 2004-2006 lava domes indicate that extrusion of the new lava dome continues, despite relatively low seismicity levels. Mount Rainier's M 4.5 earthquake at about 7:50 PM last night registered on the Mount St. Helens seismic network. 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_sch eme.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 Mount Rainier: At about 7:50 PM on Saturday evening, a magnitude 4.5 earthquake occurred 7-8 miles east of Mount Rainier at a depth of about 2 miles. The earthquake has been followed by about 20 smaller aftershocks in the same area. These shallow, tectonic earthquakes are not unusual for this area and are similar to earthquakes observed in the early 1970's at Mount Rainier. All other volcanoes in the Cascade Range are all at normal levels of background seismicity. These include Mount Baker, Glacier Peak, 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. ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
