2005-03-10

 

USGS Update 2005-Mar-10 09:45

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 southeastward at higher altitudes, but remain very near the volcano at lower 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 fall in trace amounts 100 miles or more downwind.

Recent observations: The volcano is clear this morning and sporting an intermittent steam plume. There have been no explosive events since 5:25 p.m. local time on Tuesday. After the event Tuesday, seismicity returned to a level similar to that in the several hours prior to the explosion, and it remains at about that level at this time. Yesterday, the new dome was found to be remarkably intact. Ballistics up to ~1 m in diameter were hurled as far as the northern flank of the old dome. No ballistics were found along or beyond the crater rim. Ash deposits were found along a narrow eastward swath. Ash up to ~1 inch thick was deposited along the east flank of the volcano. Although no obvious vent was observed, the distribution of ballistics and ash suggest the explosion emanated from a source very near that of the October 1, 2004 and January 16, 2005 explosions. Today, crews will conduct more visual observations, measure gases, do routine maintenance on some far-field instrument stations, and redeploy GPS units.





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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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