Monday, May 29, 2006 11:30 a.m. PDT (1830 UTC)
MOUNT ST. HELENS UPDATE
Current status is Volcano Advisory (Alert Level 2); aviation color code ORANGE: 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, changes in the level of activity can occur over days to months. The eruption could 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: 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 east to southeastward early shifting to southeastward by afternoon.
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.
Recent observations: At 9:08 a.m. PDT (1608 UTC) a large rockfall from the growing lava dome corresponded with a magnitude 3.1 earthquake, sending a flow of rock and dust from the new dome. Pilots reported a plume to 16,000 to 20,000 feet. Remote camera views from six minutes after the event showed mostly steam and minor ash plumes in the crater. There is no evidence of an explosion associated with this event. Events such as this are expected during lava dome growth. Weather permitting, scientists will be in the field later this week.
http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/current_updates.html