Cloudy weather obscured the top of Mount St. Helens on Wednesday morning, making it difficult for visitors to see the volcano's crater after several days of steam and ash eruptions.
Earthquake activity in the mountain was relatively low, U.S. Geological Survey spokesman John Clemens said from the agency's Cascades Volcano Observatory at Vancouver.
"After the big show yesterday morning seismic activity has dropped off, with individual earthquake events becoming smaller," Clemens said.
Since Friday, the southwest Washington volcano has been venting steam and small amounts of fine volcanic ash. Tuesday's blast threw ash thousands of feet into the air, lightly coating cars and businesses miles away to the northeast.
Geologists have said the most likely scenario is weeks or months of small-scale venting, with the possibility that some lava could enlarge the dome within the 8,364-foot mountain's gaping crater. In the last several days, the roughly 1,000-foot-tall lava dome has risen by about 150 feet.
Scientists are predicting nothing like St. Helens' May 18, 1980, eruption, which killed 57 people, stranded thousands of travelers and closed schools and businesses. Ash then fell as far away as Montana.
In Randle, a community of 2,400 about 20 miles northeast of Mount St. Helens, postmaster Paulette Hedlund gave her two mail carriers face masks to ward off any airborne ash. Wearing the masks is up to them, she said.
"If you've been through it, you know enough to shut your windows, turn off the air pumps, don't let the kids play outside," said Hedlund, who wore out three vacuum cleaners cleaning up the abrasive ash in the year after the volcano's dramatic 1980 eruption.
A fine film of the grey stuff could be seen covering sidewalks and cars early Tuesday morning. The residents tell CBS Radio News it's more of a nuisance than anything.
"The ash fills up the air filters in the machines and your vehicles don't drive very well," said resident David Farish.
Scientists said Tuesday's steam burst opened two small new vents in the crater's floor, and that the floor continued to lift, a sign that magma was still building beneath the volcano.
Since Sept. 23, thousands of tiny earthquakes have shaken the mountain, the most seismic activity at the peak since the months following the 1980 blast.
Earthquakes trailed off after Tuesday's burst, dropping in both magnitude and frequency, said Bill Steele, spokesman for the University of Washington seismology lab in Seattle.
"We don't really know what it means at this point as far as a prognosis," he said.