Mount St. Helens roared to life again with two distinct eruptions today, belching a lightning-streaked cloud of stream and ash 44,000 feet skyward and sending another cloud to 36,000 feet six hours later.
Scientists said the second blast was accompanied by strong barmonic tremors, and aerial observers reported sighting glowing gases at the base of the column.
During the initial eruption in late afternoon -- which lasted for more than two hours -- the volcano sent a surge of superheated gas and ash over the rim of its mile-wide crater. The second pulse came late tonight.
The two volcanic pulses marked the fifth major eruption since the mountain rumbled awake last March from a 123-year slumber.
There were no immediate reports of injuries after the 4:28 p.m. (PDT) eruption, which lasted about 10 minutes. People in the restricted red zone around the volcano were evaculated earlier following some seismic activity.
Observers in aircraft and the National Weather Service charted the course of the plume to the east-northeast.
Weather Service officials in Spokane said it appeared that the cloud would cover a cone-shaped area of eastern Washington. A spokesman for the Weather Service said low-level winds could drop ash along the Columbia River basin in southeastern Washington and northeastern Oregon.
Clear weather made the ash plume visible in Portland, 60 miles south of the peak.
Harmonic tremors -- rhythmic vibrations that scientists say indicate the movement of magma or molten rock in the volcano -- were recorded at the University of Washington seismic research center in Seattle earlier today. They gradually increased and continued through the eruption.