Cascade Range Current Update

Mount St. Helens Update 5 October 2004 7:00 A.M.

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.



Past Updates

News and Current Events