New quakes from fracking, not wastewater wells

The oil prospectors of Oklahoma, it appeared, finally had a solution to their earthquake problem.

Ordered by regulators to curb the wastewater they were dumping deep into the ground, they watched with satisfaction as tremors plunged to fewer than two a day from more than five. This seemed to be important confirmation of what had long been suspected in the petroleum-dependent state: The act of drilling for crude wasn’t the big problem; it was just the way the main byproduct was being discarded.

But quakes are popping up in a relatively new corner of Oklahoma’s shale patch and sparking jitters once again. It’s not the number (so few that officials are just starting to record them) or force (very low) that’s worrisome. It’s the circumstances, because in the shale fields where the earth is suddenly moving, almost no wastewater is jettisoned underground.

That, in turn, has brought critical attention back to fracking, the essential technology that has made the oil business viable in countless low-margin fields, helping to push U.S. output to 10 million barrels a day for the first time in four decades.

Oklahoma lawmakers and regulators aren’t inclined to put heavy brakes on the use of a tool that has helped to triple output in the state in the past decade to 497,000 barrels a day, creating thousands of jobs. The state, the nation’s fifth-largest producer, was among the first to forbid cities and counties from banning fracking activities.

To some industry defenders in Oklahoma, low-level tremors now and again are a fair price to pay. In any event, these are so minor that experts are still puzzling over their significance.

But “all earthquakes start out small,” said Austin Holland, a supervisory geophysicist with the U.S. Geological Survey in New Mexico who worked for the Oklahoma Geological Survey until 2015. “You can’t rule out the possibility that you could have a significant earthquake triggered by hydraulic fracturing.”