USGS Update 2005-Jan-15 11:00

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 westward at low altitude and eastward at higher altitudes early, becoming northward at low altitude and northeastward at higher altitudes later in the day.

Recent observations: Field crews had a successful day in the field yesterday. An instrument package containing a video camera and gas sensor was installed between the new and old lava domes and will send back a scene every five minutes of the north end of the new lava dome, which is the end at which lava is actively extruding. A “spyder” containing a GPS unit and a seismometer was slung by helicopter onto the north end of the new lava dome. The spyder was visible on the video images. Both packages will aid us in closely tracking the movement and growth of the new lava dome and in better understanding seismic signals. Geologists also collected new rock and ash samples and technicians serviced one of the seismic stations on the outer flanks. The dome continues to grow and fracture. A large slab on the west side of the dome had collapsed recently and had generated a small rock avalanche and ash cloud that had drifted over the south crater rim. A bright glow on the VolcanoCam seen Thursday night was likely caused by this event.

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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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