Now plot those quakes on either side of the line drawn on the map...we know the faults can extend as discussed by Jack Reed in SC, and possibly into OK as well.

Ouachita orogeny
Ouachita Mountains of Arkansas and Oklahoma is an orogenic belt that dates from the late Paleozoic Era and is most likely a continuation of the Appalachian orogeny west across the Mississippi embayment - Reelfoot Rift zone.

[link to www.worldwizzy.com]