Study: Quake risk rising in Oklahoma, Kansas

Small earthquakes shaking Oklahoma and southern Kansas daily and linked to energy drilling are dramatically increasing the chance of bigger and dangerous quakes, federal research indicates.

This once stable region is now just as likely to see seriously damaging and potentially harmful earthquakes as the highest-risk places east of the Rockies.

Still it’s a low risk, about a 1-in-2,500 years’ chance of happening, according to geophysicist William Ellsworth of the U.S. Geological Survey.

“To some degree, we’ve dodged a bullet in Oklahoma,” Ellsworth said after a recent presentation to the American Association for the Advancement of Science.

Federal records show that since Jan. 1, Oklahoma has had nearly 200 quakes that people have felt. The frequency of the quakes started to increase in 2008.

They are mostly in areas with energy drilling, often hydraulic fracturing, a process known as fracking. Many studies have linked the increase in small quakes to the process of injecting wastewater deep underground because it changes pressure and triggers dormant faults.

Until now, those quakes were mostly thought of as nuisances. But Ellsworth’s continuing study showed the mere increase in the number of tiny temblors raises the risk of earthquakes that scientists consider major hazards.