Oklahoma authorities have shut down access to dozens of wastewater wells, after a 5.6 magnitude earthquake.
The finger has been pointed at the fracking industry, which extracts oil and gas from the ground by shooting a highly pressurised combination of water, sand and chemicals into layers of rocks.
The waste water is then deposited into underground wells, which can sit near or on fault lines, which increase the risks of earthquakes.
U.S. correspondent Richard Arnold told Mike Hosking officials find themselves in an unprecedented situation.
"State officials are closing off some of these disposal areas - just how much protection that will provide now that this fracking process has been going for years is unclear."
Arnold said recent events are a part of a spike in earthquake activity.
"A decade ago, they would experience maybe two small tremors a year. But when they started doing fracking to release oil and gas deposits it began to spiral, last year they had not two, but 890."