2004-11-27

 

USGS Update 2004-Nov-27 10:15

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

Recent observations: Aerial views taken late yesterday afternoon show that growth of the welt and lava dome continue. Most of the east arm of the crater glacier that is adjacent to the welt is now deformed. Ice close to the welt is steeply inclined and intensely fractured; farther away the ice surface is beginning to rumple into broad ridges as the welt grows eastward. A magnitude 3.1 earthquake occurred at a shallow level in the crater about 5 a.m. this morning--the first earthquake greater than M3 that has been recorded since the new lava dome emerged in mid-October. It appears to be a larger version of the small earthquakes that have been occurring for many weeks at the rate of about one per minute. We hope to take advantage of good weather on Sunday or Monday to get in the field for a variety of activities.





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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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