A magnitude 3.9 earthquake that hit near Mount St. Helens early Wednesday was followed by a swarm of aftershocks. This earthquake swarm is sparking fears that the volcano could be awakening once again.
The first earthquake hit east of Mount St. Helens, 23 miles south-southeast of Morton, just after 12:30 a.m. Wednesday, according to the Pacific Northwest Seismic Network. Nineteen aftershocks have followed with the largest being 2.7 in magnitude.
Mount St. Helens, 96 miles (154 km) south of Seattle, Washington and 50 miles (80 km) northeast of Portland, Oregon, is part of the Cascade Mountain Range that runs from northern California to British Columbia, Canada. It isn’t the only active volcano in the region. In fact, there are 12 other major volcanoes and nearly 3,000 other volcanic features in the Cascades but scientists consider Mt. Saint Helens the most active within the past 10,000 years.
Seismologists said they are confident the earthquake was a tectonic event and not related to magma activity within the volcano itself, but were also rather careful to point out that the location and strength of the quake were atypical. “We have had a lot of small, tiny earthquakes in this zone. What we haven’t had is an earthquake that size, a 3.9 in that area,” said Bill Steele with PNSN.
Although the large quake happened on the east side of Mt. Saint Helens, seismologists primarily expect to see are smaller swarms of quakes on the west side of the mountain. People from Mountlake Terrace to Seattle and from Portland to Astoria told KIRO 7 they felt the quake. Others in Glenoma, Randle, Morton, and other towns along Highway 12 in Lewis County told KIRO 7 they felt some significant shaking. No damage was reported.
“The trains running, the cars, the airplanes landing, there are a lot of things you can do with just a few seconds of warning,” said University of Washington seismologist John Vidale. Scientists are working on plans to give a 7 to 10-second warning in the event of a major seismic event near Mt. Saint Helens.
University of Washington seismologists say they log about 17 earthquakes a month on average near Mount St Helens, however, in the past month, they have tracked more than 80. But they say there is no cause for concern although these tremors appear very strange, to say the least.