Oklahoma’s strongest earthquake has been linked to the oil industry
A new study in the journal Geology is linking Oklahoma’s November 6th, 2011, earthquake to the injection of wastewater deep underground — water that’s used both in fracking and the extraction of petroleum from conventional oil wells. The 5.6 magnitude quake, the most significant to ever hit the region, injured two people, cracked highways, and damaged over a dozen homes.
After the 5.7 quake hit Prague, Oklahoma, it was followed by another 5.0 quake and thousands of aftershocks. Interestingly, the wastewater had been pumped into abandoned oil wells for 17 years without incident. The geologists speculate that, as the wastewater replenished compartments once filled with oil, the pressure to keep the water going down had to be increased. And as this pressure built up, the fault jumped; changes in water volumes deep underground reduced the stress on the rock, allowing the fault to slip. And in fact, this “Wilzetta Fault” was only 200 meters away from the active injection wells.