2005-10-09

 

USGS Update 2005-Oct-09 10:45

Potential ash hazards: Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), coupled with eruption models, show that any ash clouds that rise above the crater rim today would drift east-southeastward early in the day and southeastward later.

Recent observations: Rainfall during the past couple of days hasn’t been sufficient to generate significant flows of water and rock debris from the crater. But events during the last two days of September at Mounts Rainier and Hood serve as reminders that onset of autumn rains and intense rain-on-snow events later in the autumn and winter can trigger debris flows at Cascade volcanoes. The crater of Mount St. Helens with its snow and ice, abundant debris, and a growing lava dome is susceptible to such events, which, in addition to storms, can also be generated by hot rock avalanches from the dome that swiftly melt snow and ice. Areas in the crater and on the Pumice Plain north of the volcano and upper North Toutle River valley above the Sediment Retention Structure are at greatest risk from such events





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Standard USGS Update

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 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.

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.

My intent with this page is to provide a clearning house for links to the current activity at Mt.St.Helens. Please send me any links of interest that you may come across, whether for permanent sites or for news reports. I'm not going to be able to do this all alone and all help will be appreciated.

(Disclaimer— I have no association with anyone or any organization, and speak only for myself. Links and quotes are provided for information only.)

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