The Cascadia Subduction Fault extends from British Columbia down the West Coast and off in the Pacific Ocean, terminating in Northern California. This earthquake from its position on the map looks like it would fit a Cascadia Fault earthquake event.
One of the possible scenarios is that the seismologists have postulated is that the subduction fault may not "rip" the entire length of the fault zone, but only a portion of it.
No Tsunami warning though, so maybe another fault zone out there in the ocean?
