Strong earthquake in key state of fracking in America.

[-DarkJesús-]

Washington. - A strong earthquake shook Oklahoma on Saturday in the central United States, where the seismic incidence has increased amid the boom of the controversial hydraulic system mineral fracturing to extract oil and gas.

The US Geological Survey said the quake, with a magnitude of 5.6 degrees was recorded at near Pawnee, a town northwest of the state, AFP reported.

The tremor was felt in six other states, from Texas to Iowa.

"There have been fires, or injuries were reported, are very fortunate," he told Fox News Brad Sewell, mayor of Pawnee.

Saturday's quake was equal to stronger than has been recorded in the history of the last decade in this state the central United States, the Geological Survey said.

The main cause of human-induced earthquakes in many parts of the central United States is the use of sewage, according to a report released in March by the service.

A source of sewage comes from hydraulic fracturing or fracking known as method, which uses water with sand and chemicals into deep parts of the earth to open rock formations and extract oil and natural gas.

Oklahoma is an area with high seismic activity, although the tremors usually have a low intensity.

The quake was relatively close to the city of Tulsa, the most populous state.

The quake has had, on preliminary data, the same magnitude as the earthquake of November 2011, which marked a record high occurred near wells and hydraulic fracturing or "fracking". Experts believe that the number of earthquakes in the state of Oklahoma has increased this practice, but the magnitude is usually much lower and be around 3 degrees Richter.

Oklahoma Gov. Mary Fallin announced the dispatch of experts to review the wells of "fracking" in the quake zone, according to local Fox channel in Tulsa.