Earthquakes in Oklahoma City

Oklahoma City has an unusual earthquake risk profile: naturally low, but dramatically elevated in recent years by human activity. Beginning around 2009, the region experienced an extraordinary surge in earthquakes caused not by natural tectonics but by the deep underground injection of wastewater from oil and gas operations, which increased pressure on ancient faults and triggered them to slip. Oklahoma went from a handful of felt quakes a year to hundreds, briefly making it one of the most seismically active places in the lower 48 states.

The largest of these induced events was the magnitude-5.8 Pawnee earthquake of September 2016, the strongest ever recorded in Oklahoma, felt across several states and causing structural damage. The magnitude-5.7 Prague quake in 2011 also caused injuries and destroyed homes. After state regulators sharply curtailed wastewater injection volumes, earthquake rates fell substantially, demonstrating the direct link between the injection practices and the seismic swarm around Oklahoma City.