Although fewer in frequency, the swarm of earthquakes approximately 250 miles off the central Oregon coast continued Thursday for the third consecutive day.
The swarm of quakes began early Tuesday morning, producing over 60 quakes of 3.5 in magnitude or greater Tuesday and Wednesday, adding 16 more quakes in the same 75 mile radius some 250 miles off the central Oregon coast Thursday, as well as two additional quakes off of Depoe Bay and Bandon.
The quakes continue to concentrate on the Blanco Fracture Zone, not considered by the US Geological Survey to be a megathrust fault that displaces seafloor and ocean water to form tsunamis, as compared to the Cascadia subduction zone that lies 220 miles to the east.
Thursdays quakes again began very early in the morning with a series of four 3.2 to 3.8 magnitude quakes beginning near midnight and continuing to approximately 5:30am, before a 4.6 magnitude quake just before 7:00am started a series of four quakes 4.1 to 4.6 in magnitude. Seemingly increasing in magnitude as the day progressed, the first of two quakes registering 5.0 or greater struck, with a 5.2 just after 1:00pm and a 5.4 just after 3:30pm, Thursday afternoon.
Again, all of the quakes were considered relatively shallow at just over 6 miles deep, with little displacement, generating no tsumani warnings, alerts or tsunami waves.