VolcanoCam Movies Archive

USGS Mount St. Helens Information Statement
October 4, 2004, 7:00 pm, PDT

(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 12,000 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 lake. 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.