More than 70 earthquakes hit Oklahoma this week, causing alarm over drilling in the state.
State officials at the Oklahoma Geological Survey warn that drilling for oil and natural gas may be the culprit, particularly the use of injection wells, reports USA Today. “The OGS considers it very likely that the majority of recent earthquakes, particularly those in central and north-central Oklahoma, are triggered by the injection of produced water in disposal wells,” the agency announced.
Earthquakes have become a common occurrence in states like Texas, Kansas, Arkansas, Colorado and Oklahoma—where the state has seen an uptick in magnitude-3 or greater quakes, from 109 in 2013 to 585 in 2014, according to USA Today. This past year is still being computed.
Injection wells are deep depositories for drilling byproducts and wastewater and the injected water changes the friction of naturally occurring fault lines, unleashing the quakes. State officials have called on well companies to either scale back or stop injection operations completely. Some have been ordered to cut the amount of water they are injecting for disposal by up to 50%.