More than 400 earthquakes have been detected beneath Washington's Mount St. Helens in recent months, though there are no signs of an imminent eruption, according to the U.S. Geological Survey.
Most of the quakes over a three-month span beginning in mid-July were less than magnitude 1.0 and too small to be felt at the surface, the agency reported last week. Small magnitude earthquakes detected with sensitive equipment signal a volcano is “recharging” as magma flows through chambers and cracks deep underground, Wes Thelen, a volcano seismologist with the agency's Cascade Volcano Observatory told The Columbian newspaper.
