The reality is that quakes are treated by the anti-drilling lobby as a proof of "me am play gods"[1]. A sign from above/below that we're angered mother earth. I think the more sober minded should realize that the important numbers when talking about "consequences" is not how angry mother earth is, but the quakes' cost in terms of damage and human lives.
The roads in most of the fracking areas are terrible and its often hard to pinpoint whether damage was caused by heavy fracking trucks simply driving on these small roads frequently versus seismic activity versus something else. That doesn’t mean there isn’t damage, it’s just difficult to account for and externalized.
More significantly, there are major changes inside the earth that occur. If you pump a bunch of poisonous fracking fluids into the ground and then drill out a bunch of shale, you’ve replaced a solid layer of shale with fracking fluids and air. Naturally things can mix more since there isn’t a tough layer of shale. The shale is normally pretty close to the aquifer layer which means you now have seismic activity mixing your fracking fluids and shale remnants with your drinking water. Just because the layman may not immediately see the consequences, doesn’t mean they aren’t there. And in most of the big fracking areas there are enough houses without drinkable water that people know something bad is happening even if they can’t pinpoint the exact mechanism. If you drive around those areas, you’ll notice many houses with what are known as water buffalo tanks outside to provide their house with drinkable water. Typically the gas company pays for these because the families in the area have threatened lawsuits or other action after their houses lost drinkable water.