Now Fracking Activity Is Probably Causing Earthquakes in Texas, but I learned an important detail. "It’s not the fracking itself that’s driving North Texas’s quake spike, but the wastewater injection wells. That’s when oil and gas companies shove brine and other fracking byproducts back into the ground, irritating faults."
Last July, io9 explained, Can We Please Stop Blaming Fracking For Every Induced Earthquake?
I'm seeing a lot of stories covering the link between injection wells and induced earthquakes in Oklahoma, but most of them make the same error: this study had nothing to do with fracking. The injection wells in Oklahoma causing the swarms of small-magnitude earthquakes are used to dispose of wastewater from dewatering operations. These particular wells are still part of oil and gas production, but don't fracture the surrounding rocks. Instead, extraction wells suck up water already in the formation. After yanking out the oil and gas, the leftover wastewater is injected back into the ground. The change in water pressure distribution induces the earthquakes, some quite far away from the actual wells.
This isn't to say that fracking is safe and harmless. Fracking probably does induce earthquakes, maybe even some of the earthquakes in Oklahoma. On top of that, the fluids have a nasty habit of sneaking into the groundwater. But fracking is not dewatering, and the particular story making the rounds in the news circuit isn't about fracking.