Associated Press
PORTLAND, Ore. — Mount St. Helens was subdued Monday following a weekend in which thousands of small earthquakes were detected.
The quakes started Friday night and continued almost unabated on Saturday. But the numbers began dropping Sunday and continued to decrease MoZnday afternoon, said Bill Steele, coordinator for the University of Washington’s seismology lab.
"We’re not looking at these as any kind of precursor to eruptive activity," Steele said. "There’s no indication of new magma being injected into the volcano that could lead to an eruption."
The quakes have been happening about a half-mile below the surface, most under the north flank of the 826-foot-high lava dome in the volcano’s crater.
The largest quake detected was a magnitude 1.9 on Sunday.
Researchers with the Cascades Volcano Observatory in Vancouver, Wash., said the quakes are likely related to increased rainfall. The water percolates into the lava dome and crater floor, causing fractures to slip.
The quakes may increase the likelihood of small landslides, debris flows and small steam explosions.
Mount St. Helens erupted on May 18, 1980, killing 57 people. The last dome-building eruption, in which magma reached the surface and added to the pile of lava on the crater floor, was in October 1986.
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