Two new studies explain why frequent earthquakes are more likely in some fracking zones, according to a Live Science article. The first study analyzed nearly 4,000 earthquakes in Oklahoma to detect both unknown and known faults, finding that most of the hidden faults were under pressure. Researchers say injecting fracking wastewater into the ground increases the faults’ volatility.
The second study found that faults in North and South Dakota and Montana weren’t under as much pressure and were less prone to earthquakes, even with fracking liquid injections. Researchers believe that the states’ geology and the amount of fracking waste water being injected may play roles in the limited activity.