Record quake in Oklahoma leads to shutdown of wastewater wells

New York Times : On 3 September a magnitude 5.6 earthquake struck central Oklahoma, tying the record for the strongest quake in the state’s history. The region near the quake’s epicenter experienced moderate damage and a few non-life-threatening injuries. In recent years, Oklahoma has seen a significant increase in seismic activity. In 2009 only three earthquakes of magnitude 3.0 or above occurred. In 2015 there were 907. Many seismologists believe that the increase in activity is tied to the high-pressure injection of wastewater from oil and gas wells into Earth’s crust. Oklahoma has thousands of such disposal wells throughout the state. The pressurized water finds its way through the surrounding rock and alters stresses along old fault lines, which allows them to slip. The US Geological Survey said that although there is a connection between wastewater injection and the rise in number of earthquakes, it can’t yet directly tie the recent quake to the practice. Nonetheless, the Oklahoma Corporation Commission, which oversees drilling activity in the state, ordered the shutdown of about 36 wastewater wells in a 1295 km² area around the quake’s epicenter.