Cascade Range Current Update |
U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington
Volcanoes in the Cascade Range are all at normal levels of
background seismicity except for Mount St. Helens. See Mount St.
Helens
update below.
Other volcanoes include Mount Baker, Glacier Peak, Mount
Rainier, and Mount Adams in Washington State; Mount Hood,
Mount Jefferson, Three Sisters, Newberry, and Crater Lake, in
Oregon; and Medicine Lake, Mount Shasta, and Lassen Peak in
northern California.
USGS Cascades Volcano Observatory, the Pacific Northwest
Seismograph Network at the University of Washington, and the
USGS Northern California Seismic Network and Volcano Hazards
Team in Menlo Park, California, monitor the major volcanoes in the
Cascade Range of northern California, Oregon, and Washington. Mount St. Helens Update, October 12, 2004, 7:00 a.m, PDT Current status is Volcano Advisory (Alert Level 2); aviation color
code ORANGE Seismic activity remained at a low level overnight. Small
earthquakes (maximum about magnitude 1) continue to occur at a
rate of about 1 per 5 to 10 minutes. Visual observations and
thermal imaging of the crater, the 1980-86 lava dome, and the
intensely deforming and uplifting area on the south side of the
dome were made yesterday afternoon. Thermal imaging of the
western part of the uplifting area revealed temperatures of 500 to
600 degrees C on a large pinkish-gray fin of rock and in nearby
fumaroles and cracks. These observations are consistent with
new lava having reached the surface of the uplift. Additional visual
and thermal observations will be made today to further evaluate
this interpretation. A gas-sensing flight yesterday measured fluxes of sulfur dioxide
and carbon dioxide that are similar to or slightly smaller than those
measured on 7 October. The next gas-sensing flight is scheduled
for tomorrow. Wind forecasts from the National Oceanic and Atmospheric
Administration (NOAA), combined with eruption models, show
winds this morning will remain northwesterly. Any ash clouds will
drift south-southeastwardly to southeastwardly. As a result of the intense unrest of the past two weeks and
yesterday’s observations, we infer that magma is at a very shallow
level, and perhaps at the surface. During times of unrest, Mount
St. Helens and similar volcanoes elsewhere typically go through
episodic changes in level of unrest over periods of days to weeks,
or even months. Such changes are in part driven by variations in
the rate of magma movement. We expect fluctuations in the level
of unrest to continue during coming days. Escalation in the degree
of unrest could occur suddenly or with very little warning. There
may be little time to raise the alert level before a hazardous event
occurs. Therefore, we continue to monitor the situation closely and
will issue additional updates and changes in alert level as
warranted. Today’s media briefing will be held at the Headquarters of the
Gifford Pinchot National Forest at 10:30 a.m.
|
Return to:
[Cascade Range Current Activity Menu] ...
[Mount St. Helens Current Activity Menu] ...
[News and Current Events Menu] ...
Go to:
[Cascade Range Volcanoes and Volcanics Menu] ...
[Mount St. Helens Menu] ...
Link to:
[USGS Volcano Hazards Program Updates Page (includes Alaska, Hawaii, and Long Valley)] ...
[University of Washington's Pacific Northwest Earthquake Information (current seismicity)]