USGS Update 2005-Jan-26 10:15

Aerial views taken on 2005-Jan-24

Potential ash hazards: Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), coupled with eruption models, show that ash clouds that rise above the crater rim today would drift west-northwestward to northward.

Recent observations: The volcano is obscured by clouds this morning. Although conditions for the gas-sensing flight on Monday were poor, analysis of data suggests that the emission of sulfur dioxide is about the same as in previous measurements (range of 50 to 250 tons per day). At yesterday’s press briefing there was a lot of interest in gaining better perspective about the size of the uplifted welt and new lava dome. The total volume change represented by the welt and dome as of 3 January of this year is 34 million cubic meters (or 44 million cubic yards). For Portlanders, that is equivalent to 134 Rose Garden arenas. The area of the dome and uplift covers about 60 city blocks. In Portland an equivalent area would extend from the Morrison Bridge to the Hawthorne Bridge and from the Willamette River to the Park Blocks. The top of the new lava dome rises about 550 feet above the pre-eruption surface of the flanking glacier. But the lava dome probably extends to the base of the glacier, which means that its true height is closer to 1100 feet.

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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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