USGS researchers have been circumspect about the nature of the quakes. The agency recently said that fracking "is only very rarely the direct cause of felt earthquakes." However, government scientists have focused in on wastewater injection associated with fracking, with the process drawing more scrutiny as reports of earthquakes become more frequent.
Experts say those injection wells, a byproduct of shale drilling, are a growing issue that oil and gas producers need to address.
"The overall uptick in earthquakes in the continent seems related to wastewater," Katie Keranen, a geophysicist at Cornell University and a former ExxonMobil exploration scientist, explained in an interview.
Read MoreDemocrats to Obama: Make a call on Keystone
Drillers "end up with a high volume of wastewater and put it back into another formation, and that's what's more commonly linked to earthquakes," Keranen said.
Still, even staunch fracking opponents have stopped short of drawing an outright connection between drilling and quakes.
The National Resources Defense Council said that energy production "must not come at the expense of public health and safety," but recently acknowledged the need for more research and data into the subject.
"Rather than putting a damper on the boom, it will force a drive for new technology and operations and practices," said Keranen. "We have a need for energy, and if we are going to get it, we need to do it safely."
Correction: an earlier version of this story misidentified the shale formation nearest to Oklahoma.