DENVER - Wastewater injections from oil and gas operations likely has led to the recent sharp increase in earthquakes across central Oklahoma, according to researchers, including two from the University of Colorado Boulder.
The study, which appears in the journal Science, used advanced hydrogeological models to gauge how pressure from wastewater injected into underground rock seeped into faults where seismic activity occurred.
Oklahoma averaged about two 3.0-magnitude or higher quakes per year before 2008.
Up to May 2 of this year, the U.S. Geological Survey recorded 145 quakes. That spike comes amid the state's boom in hydraulic fracturing — or "fracking," a method for extracting oil and gas that produces high volumes of wastewater.
Experts have drawn the distinction that while it's not the fracking itself that may trigger quakes, the pressurized disposal of the waste fluid underground has raised concerns.
In Colorado, a rare Greeley-area earthquake late last month prompted further examination of wastewater injection wells in that vicinity.
The Oklahoma study, which looked at data from 89 injection wells, attributed the massive increase in seismic activity — a collection of quakes known as the Jones Swarm — to a small number of high-rate wells.