The Guy Arkansas quake swarm has returned and today the magnitudes are larger with a 4 and 4.3. I would still like to know what is going on there. One obvious question is what is the upper limit on what you could have? Is there a weak ancient fault that could fire off a New Madrid-style M7+? Or, is it just some stress local max, maybe related to fluids, and there is no way a big rupture can get going?

The obvious best bet is that this round will not get much bigger: I would be a little surprised to see a M5, but possible. But, there is some tiny chance always for something bigger.
Chris