A "very small number" of disposal wells are behind a swarm of earthquakes that have plagued Oklahoma since 2009, and embroiled fracking in a new controversy, according to a study released on Thursday.
In new research conducted by geologists from Cornell University, the University of Colorado and the U.S. Geological Survey (USGS), the surge in Oklahoma's tremors may be linked to "a small number of exceedingly high-rate" wastewater injection wells. These repositories are the primary method of dumping water used in hydraulic fracturing (fracking), and are seen by scientists as a force multiplier behind an exponential increase in quakes across the country.
The study used geological models to show how migration of wastewater from key wells in the state may be the culprit behind the largest swarm of earthquakes.
Although tremors have been felt in states involved in or close to the shale boom, The Sooner State has been the epicenter of a cluster of tremors since the shale boom began. Oklahoma recorded nearly 100 earthquakes of at least 2.5 magnitude in the last month, according to USGS data, and just this week experienced two quakes of at least 3.0 on the Richter scale.