This is the largest earthquake to strike Oklahoma in 5 years time, and the 3rd largest in state history.
In 2011, a M5.6 struck Oklahoma , again at a fracking / pumping operation, at the time (in 2011) professionals actually tried to DENY that fracking caused earthquakes.
Now we know better, the 2011 M5.6 was caused by fracking wastewater injection, and now the M5.1 in 2016 is caused by the same culprit.
The pressure that mother nature is putting on the operations is proving to be far too strong for the operations to handle. The pressure is coming from the Pacific Northwest + West coast, pressing to the East along the edge of the Craton.
Full post with screenshots here: