Dr. Dziak
Dr. Dziak

This post comes to us from Dr. Bob Dziak, Acoustics Program Manager:

As many of you are probably aware, since Sunday night there has been a sequence of strong earthquakes (magnitudes 4.3-5.9) occurring on the seafloor ~250 miles west of Newport.

The earthquakes are occurring along the western Blanco Fracture Zone, a 200 mile long strike-slip fault located in water a mile deep. The Blanco forms one of the southern boundaries between the small Juan de Fuca plate and the much larger Pacific Plate.

The 2015 quakes are the large magenta circles (map created by Susan Merle).
The 2015 earthquakes are the large magenta circles (map created by Susan Merle)

Clusters of earthquakes of this magnitude occur on the Blanco Fracture Zone roughly every 3-5 years.    A tsunami warning was not issued because these earthquakes were too small and the wrong sense of crustal motion to generate a sizable tsunami. There were a few reports of weak ground motion from the earthquakes being felt on the coast, but no damage was reported. Also, as of today, it looks like the earthquake activity is on the decline.

Even though these earthquakes are not a hazard, we thought it was a good opportunity to remind the community to review their evacuation plans and make sure your emergency supply kit is ready and up to date.

Please check out these news links for more information:

USA Today


Statesman Journal

Oregon Live


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