An oil rig stands on farmland that grows barley for Coors Brewery at the Niobrara oil shale formation in Weld County, North eastern Colorado on May 30, 2012. Gas and oil companies are using large amounts of water to obtain shale oil and gas in a process called hydraulic fracturing or fracking. UPI/Gary C. Caskey | License Photo

WASHINGTON, Dec. 19 (UPI) -- Ranking Democrats serving on House energy committees have called for hearings to discuss possible seismic activity associated with hydraulic fracturing.

Reps. Henry Waxman, D-Calif., ranking member of the House Energy and Commerce Committee, and Peter DeFazio, D-Ore., ranking member of the House Committee on Natural Resources, issued a letter to their Republican counterparts requesting a hearing on the risks of man-made earthquakes.


The ranking members point to a joint October study from the U.S. Geological Survey and Oklahoma Geological Survey that suggested tremors in the state "may" be linked to hydraulic fracturing.

Hydraulic fracturing, known also as fracking, is a target of criticism by environmental groups. Waxman and DeFazio said injecting wastewater generated by fracking underground could be a potential cause of earthquakes.

"Underground fluid injection has been known to have the potential to cause earthquakes since the phenomenon was first observed in Colorado in the 1960s," the ranking members said Wednesday in their letter.

There was no statement issued by their respective Republican counterparts.

Waxman and Rep. Bobby Rush, D-Ill., called for hearings this week to examine methane emissions associated with oil and gas drilling.

Fracking in oil and natural gas deposits in the United States has put the country in a leadership position in terms of energy production.