Mount St. Helens monitoring ongoing 36 years after eruption

MOUNT VERNON, Wash. – Thirty-six years after a deadly volcanic eruption at Mount St. Helens, the United States Geological Survey is still closely monitoring the volcano and others in the state.

The Skagit Valley Herald reported the USGS monitors volcanoes in Washington and Oregon’s North Cascades region through its Cascades Volcano Observatory and activity this year has been considered normal. The agency issues weekly reports on seismic activity near the volcanoes.

Washington’s five major volcanoes are Mount Rainier, Mount Adams, Mount Baker, Mount St. Helens and Glacier Peak.

Mount St. Helens erupted on May 18, 1980, killing 57 people and eventually sending volcanic ash around the globe. According to the geological survey, more than 130 small earthquakes were detected beneath Mount St. Helens between mid-March and early May, and the rates steadily increased from March, reaching nearly 40 per week.

A post on the survey’s website on May 5, says “there are no signs of an imminent eruption,” and the quakes are part of common activity at the volcano.

Another recent swarm of earthquakes at Mount Hood this week were deemed by the survey to not be linked to “magmatic processes” but to pre-existing tectonic fault lines.

“Swarms are not uncommon in the Mount Hood area, which typically experiences one or two swarms per year that last for several days to weeks,” says a Monday post.