After averaging 2 significant earthquakes per year for 30 years, Oklahoma's magnitude 3.0 or greater earthquakes shot up to 145 in less than half of this year. The jump in earthquakes coincides with (SURPRISE!) Oklahoma's beginning fracking operations.
Today Oklahoma experienced a 4.2 magnitude earthquake. That's significant. It would seem that perhaps fracking can produce big earthquakes, too, not just lots of small ones.
Although the powers that be in Oklahoma, and elsewhere, still won't admit that all the earthquakes are caused by fracking. Just a coincidence, you know.