Mount St. Helens ‘Actively Going To Sleep’

Eighteen years after an eruption that killed 57 people, volcanic activity continues to subside at Mount St. Helens.

The few weak earthquakes occurring each month beneath the 8,366-foot volcano seem to indicate more cooling and settling, say geologists at the Cascades Volcano Observatory of the U.S. Geological Survey.

“It’s more actively going to sleep, if you will,” geologist Dan Dzurisin said. “When volcanoes are quiet, they are very quiet. And when they are quiet, no matter how hard you listen, they are not doing much.”

The explosion of May 18, 1980, pulverized the top 1,300 feet of the oncesymmetrical peak, flattened 230 square miles of forests, triggered mudflows that choked nearby rivers and covered Eastern Washington with a thick layer of volcanic ash.

The last eruption, in 1986, was a quiet oozing of thick molten rock that added to the bulk of a lava dome in the gaping horseshoe-shaped crater, but another round of activity is likely within decades, Dzurisin said.

“Mount St. Helens is the most frequently active volcano (in the Cascades). If you had to put money down, you would still bet that it is the most likely volcano to erupt next,” Dzurisin said.