Johnston Ridge Observatory
24000 Spirit Lake Highway
P.O. Box 326
Toutle, WA 98649
VolcanoCam Movies Archive
Eruption Event Movie - October 04, 2004
Please Note: This Flash movie is very large (6.14 MB). The
movie will commence as it downloads to your computer, but at a slower frame
rate than it was originally recorded. Once the entire movie has downloaded,
the frame rate will increase to its defined rate of six frames/second.
For maximum enjoyment, allow the movie to download completely. The movie is
preset to loop indefinitely.
Below the Flash movie may be a copy of the press release as issued the same day
by the U.S. Geological Survey, Cascades Volcano Observatory, Vancouver, Washington.
Download Your Own Movie
This movie is also available for download in the following formats: .avi,
.mov, and .wmv. See movie caption below for details.
(As issued by the U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington)
This morning visitors to Mount St. Helens witnessed a 40-minute-long
steam-and-ash emission starting at 9:43 PDT. Steam clouds carrying
minor ash billowed out of the crater to an altitude of 10,000 to perhaps
feet. The event did not generate earthquakes or an explosion signal.
We infer that hot rock was pushed up into the glacier, melted ice,
and generated the steam. Part of the vent for today’s and other
steam and ash emissions of the past few days is now covered by a boiling
The emission occurred during a time of gradually increasing seismicity,
which dropped slightly after the emission, but continued to increase
gradually through the afternoon.
Another period of smaller steam and ash bursts occurred between 2:10
and 2:40 P.M. Visual observations show that the area of uplift, which
includes part of the glacier and a nearby segment of the south flank
of the lava dome, continues to rise. We infer that magma is at a very
shallow level and could soon be extruded into the vent or elsewhere in
the deforming area. Additional steam and ash emissions are likely and
could occur at any time without warning. Conditions suggest that there
is also an increased probability of larger-magnitude and more ash-rich
eruptions in coming days.