USGS Update 2004-Dec-18 10:30
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 southeastward early in the day. Later in the day, ash clouds would drift northward at low altitude and eastward at higher altitude.
Recent observations: This morning, a white vapor plume is again visible rising above the crater rim and drifting off southward. The gas-sensing flight cancelled by Thursday’s conditions took place yesterday. Results should be available in the update tomorrow or Monday. No field work is planned for the weekend. Similar to Thursday night, three more earthquakes of magnitude 2.7 to 3.1 occurred last night amidst the ongoing pattern of frequent smaller earthquakes. Such swarms have occurred on several occasions during the past month.
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.)