Oklahoma residents had a bumpy weekend ... literally.
On Saturday and Sunday, Oklahoma experienced seven earthquakes, with the most severe registering at 4.3-magnitude. So far, there have not been any reports of injuries. (Via Earthquake Track)
Just last month, Oklahoma became the state with the most earthquakes, passing up California.
The U.S. Geological Survey says, "The rate of earthquakes in Oklahoma has increased by about 50 percent since October 2013."
Studies are currently being done by the USGS and the Oklahoma Geological Survey to find out what's behind the increase.
A possible culprit could be hydraulic fracturing, or fracking, the controversial technique that's often the target of environmental groups. (Via CBS)
Fracking involves injecting treated waste water between deep layers of rock to allow more oil and natural gas to be retrieved. It's that waste water injection some believe is causing the ground to move. (VIA KFOR)
But CNN says fracking is crucial to the state's economy, so eliminating the problem will be no easy task.
"One out of every six Oklahomans gets a paycheck thanks to the oil and gas business. It also produces 27 percent of the state's annual tax revenue."
Scientists do know that fracking has caused some earthquakes in the past, but they are currently unsure if it's behind all or any of this weekend's events.
The Oklahoma Geological Survey told The Oklahoman in 2012, "Our position is that until you can prove that it's not a natural earthquake, you should assume it's a natural earthquake."
The journal Science says in light of studies potentially linking earthquakes to fracking in the state, Oklahoma regulators are beginning to limit new operations and asking for more frequent data reports.