USGS Update 2005-May-13 09:50

Remote view taken on 2005-May-12

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 chiefly east early in the day, and east-northeastward later. Under such wind conditions, State Route 504, Coldwater Ridge Visitor Center, and Johnston Ridge Observatory should generally be spared any potential fallout from an ash plume.

Recent observations: Overall seismicity and ground deformation in the crater continue their relatively placid patterns established over the past few weeks. However, a couple of larger earthquakes (up to M2.5) were associated with rockfall collapses off the new spine. At about 1pm yesterday, a large piece of the spine collapsed and generated a small ash flow that deposited debris on the west arm of the glacier, and a plume that rose above the crater and drifted east-northeast. Another pair of rockfalls occurred about 10:35pm. Crews yesterday obtained thermal images and new photographs of the dome, conducted an extensive media interview at the mountain, and were on hand to witness the 1pm rockfall and ash plume.

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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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