USGS Update 2005-Jul-15 09:40

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 northeastward early and eastward to east-northeastward later.

Recent observations: An ~M3 earthquake at 5:22am triggered a rockfall that sent an ash plume above the rim. This is the largest quake that has occurred in some time, and its exact cause is under debate. Over the past two days, new GPS stations were deployed on the east and west arms of the glacier, along with a new seismic station on the west glacier. Measurements of CO2 and SO2 on Wednesday indicated that there has been little change in the amounts of gases emitted by the volcano. Thermal and conventional imagery show that maximum temperatures of the dome are about 660 C ( ~1200 F), and that a broad ridge along the west side of the dome continues to emerge. A digital elevation model (DEM) based on June photography should be completed soon, and photos for constructing another DEM were obtained on Wednesday. Overall, rates of seismicity and ground-deformation remain low while the dome continues to grow.

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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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