America’s Volcanoes

Current Mount St. Helens status from CVO:

Sunday, September 30, 2007 09:25 PDT (Sunday, September 30, 2007 16:25 UTC)

MOUNT ST. HELENS UPDATE
Current Volcanic- Alert Level WATCH; 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 rising above the crater rim today would drift eastward to northeastward.

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: Stormy weather with potentially heavy rains envelope the mountain today. Under these conditions, small, localized debris flows can be triggered, and sediment movement along the North Fork Toutle River can cause muddy plumes along the lower Toutle River. Seismicity at the volcano remains the same as in recent days, with small earthquakes indicative of rockfall, glacier motion, and ongoing intrusion of magma into the growing lava dome.

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