Wastewater injection wells triggered 888 earthquakes in Oklahoma in a single year

Oklahoma experienced 888 magnitude-3-or-larger earthquakes in 2015 alone, up from fewer than 2 per year before 2009, all caused by the deep underground injection of billions of barrels of produced water from oil and gas operations. Five earthquakes exceeded magnitude 5, including the 2016 Pawnee earthquake (M5.8), the largest in Oklahoma's recorded history, which damaged homes, cracked foundations, and was felt across 7 states. The people who suffer are homeowners in towns like Pawnee, Prague, and Cushing whose foundations crack, whose property insurance premiums spike or whose insurers drop them entirely, and whose property values decline. Cushing is also home to one of the world's largest crude oil storage hubs, and a major seismic event there could trigger a catastrophic spill. Why does this persist? Produced water is an unavoidable byproduct of oil production -- for every barrel of oil, up to 10 barrels of water come up. Operators need to dispose of it somewhere. Deep injection is the cheapest method. While Oklahoma regulators have reduced injection volumes and required cement plugbacks since 2015 (which reduced seismicity by a factor of ~4.4x), the fundamental problem remains: the cheapest disposal method destabilizes fault lines, and alternative methods (treatment, recycling, surface discharge) are far more expensive.