Okay, this M7.1 is old news, but I was freezing my appendages off at 30 below. Much like the Argentina earthquake was a beautiful example of subduction, this is a spreading ridge. For everything that goes down, somewhere there must be something coming up.
This did not just happen on the spreading ridge, but on a transform or adjustment fault.
Thus, it was a mixed up shear and tension earthquake (oblique normal). You can see it was on the E-W line and there was a bit of directivity, as people felt it in Ireland and Scotland, but not Labrador. Our Earth is a wonderful nuclear reactor that must get rid of the excess heat, or risk a real melt-down. At the subduction zones the oceanic crust is old, cold, and dense, sort of like the people at the old company. :)
This stuff must sink down into the primordial ooze (compulsory retirement age). At weak zones, the crust is pulled apart, and this is reflected in the earthquake mechanism. I used to think there was ridge push, but then we'd have compressive mechanisms (maybe). I just think everything is weak and oozy, just like Martin Short on that last special (yuck).