The relationship between wastewater disposal from oil and gas recovery and earthquakes is becoming clearer. In parts of the U.S. east of the Rocky Mountains, the number of earthquakes has increased dramatically since 2009.
For example, an unprecedented 5.8-magnitude earthquake struck Pawnee, OK, in 2016, damaging buildings and causing one injury when a chimney fell on a resident. It wasn’t the only earthquake to shake the usually seismically quiescent state: Since 2009, seismicity in Oklahoma has risen 900-fold.
The reason for the quakes, researchers have determined, is the practice of injecting massive amounts of wastewater deep into the earth as part of the process of oil and gas recovery. The geologic conditions in central Oklahoma are especially conducive to triggering seismic activity, according to the U.S. Energy Information Administration, because the rock underlying the formations where disposal water is being injected has existing faults. The wastewater, injected into porous sedimentary rocks typically between 1 km and 2 km deep, often travels to the heavily fractured “basement” rocks, a layer made of solid, crystalline rocks like granite. The liquids lubricate the faults in this layer, allowing...
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