SAN JOSE, California — 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 serious damaging and potentially harmful earthquakes as the highest risk places east of the Rockies such as New Madrid, Missouri, and Charleston, South Carolina, which had major quakes in the past two centuries.

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Maintenance workers inspect the damage to one of the spires on Benedictine Hall at St. Gregory’s University in Shawnee, Okla., after two earthquakes hit the area in less than 24 hours. New federal research says small earthquakes shaking Oklahoma and southern Kansas daily are dramatically increasing the chance of bigger and dangerous quakes, new federal research indicates. The Associated Press

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 presentation to the American Association for the Advancement of Science.

During the 90-minute session on human-induced earthquakes, three quakes larger than 3.1 magnitude hit northern Oklahoma. Federal records show that since Jan. 1, Oklahoma has had nearly 200 quakes that people have felt.

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 and not really threats. But Ellsworth’s continuing study, which is not yet published, showed the mere increase in the number of tiny temblors raises the risk of earthquakes that scientists consider major hazards.

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