Cascade Range Current Update |
U.S. Geological Survey, Vancouver, Washington University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington
Current status is Volcano Alert (Alert Level 3); aviation color code
RED
Yesterday visitors to Mount St. Helens witnessed a 30-minute-long
steam-and-ash emission starting at 9:43 a.m. PDT and a 10-
minute-long steam-and-ash emission starting at 14:10 p.m. PDT.
The larger one dusted roads to the the SE of the volcano with ash.
Maximum thickness of the ash at 8 km (about 5 miles) was 0.2 mm
(less than 1/8 of an inch). Neither event generated 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 yesterday’s and other steam and ash emissions of the past few
days is now covered by a bubbling lake. Since yesterday's
emissions, earthquake energy has slowly increased to previous
high values.
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. Thermal surveys of the dome
confirms the deformation. Hot cracks (40-50° C; about 100-120° F,
well below magmatic temperatures) in the dome are opening, and
dome rocks are avalanching off the dome into the lake and onto
the south crater floor. The north flank of the dome appears
thermally stable.
Yesterday’s gas-sensing flight detected carbon dioxide, often in
association with hydrogen sulfide peaks and occasional sulphur
dioxide peaks, at numerous sites around the dome and crater
floor.
Today field crews will take additional thermal images of the dome
and crater, conduct gas-sensing and geologic-observation flights,
and continue hardening GPS sites. Two additional GPS stations
were lowered by helicopter onto the 1980-86 lava dome yesterday
to aid in measuring deformation of the dome.
Wind forecasts from the National Oceanic and Atmospheric
Administration (NOAA), combined with eruption models, show that
morning winds will are from the south and west and any ash
clouds will drift northward and easterly.
We continue to monitor the situation closely and will issue
additional updates and Alert Level changes as warranted.
Press conferences will continue to be held at the Headquarters
office of the Gifford Pinchot National Forest. The morning press
conference is at 9:30 AM. |
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)]