Well, I sometimes have to retract when they take very recent earthquakes away, but there was a M6.8 a couple hours ago near a transform fault on the northern Mid Atlantic Ridge. This is on the large size for northern Atlantic...don't know if there have been any larger in the last decade in the north Atlantic. To have one that large in that position, it is likely to be strike-slip, but there is no focal mechanism up yet.
I'm up early and HW is asleep, so can't ask her about transform earthquakes. Ocean crust is usually about 5 or 6 km thick, so it seems there must be seismic rupture below the crust in the mantle lithosphere. This transform is 100s of km-long, and the epicenter is far from the ridges on either side, so the crust and upper mantle may be a bit cooler and stronger. Aftershock may outline the extent of the rupture...if they are large enough to show up on the usgs site.
Chris

• M6.8 Mid Atlantic Ridge