"Hey, this thing's exploding!" Mike Beard, a KGW traffic spotter radioed back to the station as he flew over the snow-peaked mountain around 1:15 p.m. on March 27, 1980.

He saw steam and black ash bursting from a hole in the snow.

"There is no doubt the eruption is starting," he said. "You can see ash very, very clearly against the snow."

It was the first sign of volcanic activity on the mountain in more than a century, "an event that unequivocally showed its reawakening from a 123-year slumber," the U.S. Geological Survey's office in Vancouver, Wash., said Sunday in its daily update of activity on the mountain.

That initial burst left a crater 200 to 250 feet wide near the summit. Emergency officials advised everyone within 15 miles to leave.

Harry Truman, a longtime resident of Spirit Lake, refused. Many others shared his skepticism.

Reporters, photographers and geologists packed into airplanes to get a look at the peak, causing aerial traffic jams. Pilots eventually established a rule that all aircraft had to fly counterclockwise around the mountain.

Then-Gov. Dixy Lee Ray flew near the mountain in her State Patrol plane and said the experience was "quite a thrill."

The massive May 18, 1980, eruption of the volcano 100 miles south of Seattle blew the top 1,314 feet off the 9,677-foot peak, killed 57 people and covered the region with gritty ash.

Mount St. Helens rumbled back to life most recently in late last September, with shuddering seismic activity that peaked above magnitude 3 as hot magma broke through rocks in its path. Molten rock reached the surface Oct. 11, marking a new period of dome-building that had stopped in 1986.

Scientists have said a more explosive eruption, possibly dropping ash within a 10-mile radius of the crater, is possible at any time.

The most recent eruption on March 8 sent a towering column of steam and ash billowing tens of thousands of feet into air not long after a magnitude-2 quake rumbled on the east side of the mountain.

On Sunday, the USGS said eight earthquakes ranging from magnitude 2 to 3 had struck in the past few days, comparable to a swarm of quakes that occurred in November and December.

Crews planned to conduct observation flights over the mountain once clouds and rain cleared away.