Today, University of Texas scientists plan on releasing a study linking fracking/drilling operations to 59% of detectible seismic activity in Texas over a several decade long period of time (as opposed to 13% attributed to "natural causes"). I will post the link to the story when it releases.
It really should not come as any surprise. If you pump out millions of tons of a liquid that was between rock, that rock will now be weakened and under the great weight from above move, causing quakes. Similarly, with fracking, where one pumps millions of tons of water into rock and fractures the rock, this also destabilizes a structure that was in equilibrium and causes quakes. To expect otherwise would be strange. The only surprise is just how large the quakes have been.
Americans are making a mistake thinking their political bs that lets them get away with anything applies to nature as well.
History shows again and again
How nature points up the folly of men
"Godzilla"/Blue Oyster Cult