Peninsula Daily News
News Sources
PORTLAND, Ore. — More than 50 earthquakes struck off the Oregon coast Tuesday and Wednesday, news agencies have reported.
At least nine tremors reached a magnitude 5.0 to 5.8, with the majority occurring at a shallow depth of only 10 km, CNN reported.
The earthquakes were centered far off the coast, some 200 to 250 miles west of Newport, Ore. They were not felt on land and no tsunamis were expected.
Small earthquakes strike often near Oregon’s coast, the Oregonian reported, saying they are a regular reminder of the cataclysmic earthquake geologists say will happen when the pressure building between the Juan de Fuca and North American plates breaks.
Scientists have said it is not if, but when, a 7.1 magnitude or higher earthquake will happen at the boundary between the two tectonic plates, called the Cascadia Subduction Zone. One of the largest quakes in the continental United States devastated the region on Jan. 26, 1700, from this fault, and researchers say another one is overdue.
But the swarm off the Oregon coast doesn’t necessarily signal that the “Big One” is near, Harold Tobin, director of the Pacific Northwest Seismic Network at the University of Washington, told CNN.
The fault line responsible for the quakes is the Blanco Fracture Zone, which is reportedly more active than the infamous San Andreas Fault in California, having produced more than 1,500 quakes of magnitude 4.0 or greater since the 1970s, the Oregonian said.
“There’s quite a lot of distance from these quakes to the Cascadia Subduction Zone,” Tobin said.
“Our best current understanding of how stress transfers through the crust (and mantle) would suggest that these events don’t change stress on the subduction zone appreciably.”
The National Weather Service and Pacific Northwest Seismic Network told The Associated Press that the activity was eye-catching but nothing to be extra concerned about.
