I said it was evident, that they are tied together, theory or not, my opinion is they are the cause, does my opinion carry so much weight as to change the meaning of a word?
Deep Injection wells could also be a reason for the earthquakes, but the end result is the same, they are both the result of drilling. How do you think they do that fracking? They pump water and chemicals into the ground to break up the shale, basically the same as injection.