Oklahoma is a much shakier place than it used to be and fracking is probably to blame, according to the United States Geological Survey, which warns that the central part of the state is now at increased risk of a damaging quake. The agency says that there were 183 quakes of magnitude 3.0 or greater in the six months since October alone, compared to an average of just two that size per year between 1978 and 2008, NPR reports. A major factor, it says, is probably the injection of waste water from fracking into deep geological formations, causing quakes in a "process known as injection-induced seismicity."
The USGS and the Oklahoma Geological Survey rejected theories that the huge increase in quakes could be due to natural fluctuations in the state, which has around 10,000 injection wells, notes the Tulsa World. "We hope that this new advisory of increased hazard will become a crucial consideration in earthquake preparedness for residents, schools, and businesses in the central Oklahoma area," a USGS spokesman says. "Building owners and government officials should have a special concern for older, unreinforced brick structures, which are vulnerable to serious damage during sufficient shaking."