Scientists have linked oil drilling in Oklahama to the biggest earthquake in the state's history. New research, published in the journal Geology, suggests that the expansion of wastewater, injected into Oklahoma's sealed oil wells, placed enough stress on "reservoir-bounding faults" to trigger three successive earthquakes in 2011, the largest of which measured 5.7 on the Richter scale. Previously, the earthquake was deemed by the Oklahoma Geological Survey to be the result of natural causes, but new research opens the debate over the dangers wastewater injection.

Update: this article previously echoed analysis of the study that conflated wastewater injection with fracking. We apologize for the error.