Re: Notice of Volcanic Unrest at Mt. St. Helens

From: don findlay (don_at_tower.net.au)
Date: 09/28/04 

Date: 28 Sep 2004 01:25:53 -0700

"Ralph Nesbitt" <ralph-nesbitt@sbcglobal.net> wrote in message news:<clO5d.1523$zc1.680@newssvr12.news.prodigy.com>...
> "George" <George@george.net> wrote in message
> news:xRM5d.69714$zT6.29104@bignews5.bellsouth.net...
> > U.S. Geological Survey, Vancouver, Washington
> > University of Washington, Pacific Northwest Seismograph Network, Seattle,
> > Washington
> >
> >
> > Mount St. Helens Notice of Volcanic Unrest
> >
> >
> > September 26, 2004 3:00 P.M., PDT
> >
> >
> > Seismic activity at Mount St. Helens has changed significantly during the
> past
> > 24 hours and the changes make us believe that there is an increased
> likelihood
> > of a hazardous event, which warrants release of this Notice of Volcanic
> Unrest.
> > The swarm of very small, shallow earthquakes (less than Magnitude 1) that
> began
> > on the morning of 23 September peaked about mid-day on 24 September and
> slowly
> > declined through yesterday morning. However, since then the character of
> the
> > swarm has changed to include more than ten larger earthquakes (Magnitude
> 2-2.8),
> > the most in a 24-hr period since the eruption of October 1986. In
> addition, some
> > of the earthquakes are of a type that suggests the involvement of
> pressurized
> > fluids (water and steam) or perhaps magma. The events are still occurring
> at
> > shallow depths (less than one mile) below the lava dome that formed in the
> > crater between 1980 and 1986.
> >
> >
> > The cause and outcome of the earthquake swarm are uncertain at this time.
> > Several causes are possible, but most point toward an increased
> probability of
> > explosions from the lava dome if the level of current unrest continues or
> > escalates. During such explosions the dome and crater floor are at
> greatest risk
> > from ballistic projectiles, but the rim of the crater and flanks of the
> volcano
> > could also be at risk. Explosions would also be expected to produce ash
> clouds
> > that drift downwind at altitudes up to several thousand feet above the
> crater
> > rim. Landslides and debris flows from the crater that are large enough to
> reach
> > the Pumice Plain are also possible. Such events occurred at Mount St.
> Helens
> > between 1989 and 1991.
> >
> > We continue to monitor the situation closely and will issue additional
> updates
> > as warranted, whether activity escalates or returns to background levels.
> >
> >
> > Daily updates of earthquake data and other information can be found on the
> WORLD
> > WIDE WEB at URL:
> >
> >
> http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/current_updates.html
> >
> >
> > and
> >
> >
> > http://www.pnsn.org/HELENS/welcome.html
> >
> Looks like Mt ST Helens is getting ready to play "Pop a Top Again".
> Ralph Nesbitt

"...&&The ducts are subbing....
..For me an' my gal...&&"

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