USGS Update 2005-May-27 10:00

Views taken on 2005-May-24/26

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 northwestward to northward. However, later in the day, higher-altitude clouds would drift north-northeastward. Under these conditions, Johnston Ridge, Coldwater, and the eastern parts of State Route 504 could all receive fallout from any ash clouds produced by explosions or large rockfalls.

Recent observations: Analysis of a digital elevation model produced from aerial photographs taken on 19 April shows that the new lava dome had reached a volume of 47.5 million cubic meters (about 62 million cubic meters). We have changed the method by which we compute the volume of the dome, so this figure isn’t directly comparable to results we’ve given in the past (by the older method the new volume is about 55 million cubic meters). The rate of addition of lava to the dome remains roughly constant at about 1.5 cubic meters (2 cubic yards) per second.

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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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