There has been a M4.9 followed by a M5.2 north of Puerto Rico. This is in the area of the subduction zone on this oblique left-lateral-thrust plate boundary. There have been lots of big swarms the last couple of years (at least) in this area through the Virgin Islands, but I don't know if any of these have been this large the last couple of years.

There is not yet a focal mechanism for either one. If thrust and a S-dipping, probably gently dipping plane, then they would be consistent with subduction.

Chris