[Geysers] Mt St Helens Roars Back to Life ~ TUE 3/8

[Pat Snyder]

Here's the latest from the USGS Cascade Volcanoes site. And the "whale  
back" is still there, a little worse for wear, though.
Our expected cool weather turned into a record high (70 degrees) at the  
airport--we've had great views of St. Helens all day.

The article:
  U.S. Geological Survey, Vancouver, Washington
  University of Washington, Pacific Northwest Seismograph Network,  
Seattle, Washington

  Wednesday, March 9, 2005 9:45 a.m. PST (1745 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, 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: 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-northeastward early in the day and shift to an east-southeastward  
drift later in the 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 fall in trace amounts 100  
miles or more downwind.

  Recent observations: A small but significant explosive event occurred  
yesterday at 5:25 p.m. PST. Pilot reports indicated that the resulting  
steam-and-ash plume reached an altitude of 36,000 feet above sea level  
within minutes. The main eruption pulse lasted about 10 minutes, but  
lower levels of activity persisted for at least another 15 to 45  
minutes. Within minutes of the onset of this event, we lost  
communication with 7 monitoring stations in the crater, but not with  
any stations outside the crater. The event followed a few hours of  
slightly increased seismicity that was noted but not interpreted as  
precursory activity. There were no other indications of an imminent  
change in activity. Still images from a camera at the northeast end of  
the crater mouth show a clear component of explosive vertical jetting  
associated with the event and evidence of ballistics extending at least  
as far as the north side of the old dome. Aerial photos in of the  
waning phases of the activity in conjunction with these still images  
show evidence of small ash flows having moved north and onto to old  
lava dome. There were reports of fine dustings of ash falling in  
Ellensberg, Yakima, and Toppenish, Washington between 7pm and 9pm  
yesterday. As of 2am today, the leading edge of the plume had been  
tracked to western Montana as a faint and diffuse cloud. Today, field  
crews will make visual observations and attempt to retrieve and  
possibly redeploy some of the crater instrumentation stations.

  For additional information, background, images, and other graphics:  
http://vulcan.wr.usgs.gov/Volcanoes/MSH/Eruption04/

  For seismic information: http://www.pnsn.org/HELENS/welcome.html

  For a definition of alert levels:  
http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/ 
volcano_warning_scheme.html

  For a webcam view of the volcano:  
http://www.fs.fed.us/gpnf/volcanocams/msh/

  Telephone recordings with the latest update on Mount St. Helens and  
phone contacts for additional information can be heard by calling:

  Media (360) 891-5180

  General public (360) 891-5202

And the link if you want to go to the site:
http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/ 
current_updates.html

Pat Snyder

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