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USGS Mount St. Helens Information Statement
October 5, 2004, 6:45 pm, PDT

(As issued by the U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington)

This morning the rate of seismicity was at a high, sustained level when, shortly after 9:00 a.m. PDT, the most vigorous steam and ash emission of the current period of unrest began. The emission originated from the same vent as have others this past week, as well as from another nearby new vent in the intensely deforming area on the south side of the 1980-86 lava dome. For more than one hour, steam clouds billowed from the crater. The ash content varied with intensity of steam jetting from the vent. For the first time, ash content was sufficient that it was detected by National Weather Service Doppler Radar. Steam and ash clouds reached about 12,000 feet and drifted north-northeastward. Ash forecasts warned downwind residents. Media reports indicate that a light dusting of ash fell in Morton, Randle, and Packwood, Washington, towns about 30 miles from the volcano. Nearby traffic on U.S. 12 stirred up the ash, slightly reducing visibility. We have no reports of ash falling at greater distances.

The rate of seismicity dropped during and the emission and has stayed at a relatively low rate. We infer that magma is at a very shallow level and could soon be extruded from a vent 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.