Last weekend, a swarm of seven earthquakes in just 14 hours between Saturday evening and Sunday morning in Oklahoma made national headlines.
Those seven quakes were immediately preceded by another earthquake that measured 4.3 on the Richter scale in Langston, OK, which struck at noon on Saturday. And on Monday, a quake that measuring 3.9 hit just northeast of Harrah, OK, followed in the same region just hours later by a 3.8 magnitude earthquake, data from the U.S. Geological Survey shows.
The ground in Oklahoma keeps shaking, and state, federal and independent researchers have pointed to the shale gas rush as the likely culprit for many of the tremors. Some in the state have called for a halt to fracking and wastewater injection. Others are pushing to allow the injections to continue in the hopes that more research will allow scientists to pinpoint what makes individual disposal wells pose greater or lesser risks.
The problem highlights the intractability of one of the biggest problems created by fracking and drilling: what to do with the over 660 billion gallons of oil and gas industry wastewater created every year, largely by the rush to drill for shale oil and gas. The most common answer is to pump the waste deep underground, but a growing body of research shows that the process is causing earthquakes nationwide.
Over the past seven days, Oklahoma has experienced more than 20 earthquakes, roughly half of them over 3.0 magnitude, USGS data reveals. These quakes are usually small, with little immediate damage reported, but homeowners say they fear for their foundations and some larger earthquakes over the past several years have led to hospitalizations from falls. The 4.3 magnitude quake on Sunday shattered windows and cracked the walls of a local police station.
Oklahoma has had more earthquakes than any other state in the U.S. this year, shaken by more than double the number of tremblers that have hit California, a state twice its size that sits atop the notoriously active San Andreas fault line.