Mexico M6.6 earthquake - last gasp of dying spreading ridge
This earthquake is so new they don't even have a fault plane solution for it yet. Probably oblique-shear, and it was probably lightly felt. I just like its location. It's exactly the same as that last mid-Atlantic earthquake, a transform fault near a spread. Only this one is going down! What exactly happens when a spreading ridge is swallowed by a subduction zone? You get a lot of heat under the continent, and it won't be just volcanoes any more. It'll be the Rockies with volcanoes!
Update: Exactly the same as the other mid-Atlantic one.