Federal study: Oklahoma more at risk of big damaging quakes because of increase in small ones

New federal research says small earthquakes shaking Oklahoma and southern Kansas daily are dramatically increasing the chance of bigger and dangerous quakes.

Scientists link many of these quakes to the deep underground injections of wastewater after drilling for energy in a process known as hydraulic fracturing, or fracking.

Federal records show Oklahoma has had nearly 200 quakes that people have felt since Jan. 1.

U.S. Geological Survey geophysicist William Ellsworth says the jump in these nuisance quakes increases the risk of future ones that can do serious damage.

The number of small quakes started rising in 2008 and then really soared in 2013 and 2014.

Ellsworth says it's still a low risk, with a chance of about 1 in 2,500 years, but it's among the highest east of the Rockies.