The number of Oklahoma earthquakes jumped 2,000 percent in the last two years. That dramatic spike has some folks asking whether these tremors are natural or possibly man-made.
We've had foreshocks and aftershocks, but the shock of Oklahoma being rattled by so many earthquakes still hasn't worn off.
In 2009, the Oklahoma Geological Survey recorded 50 earthquakes. Last year, that number ballooned to more than 1,000 tremors.
The Oklahoma Impact team reported speculation that the massive spike might have been prompted by Oklahoma's biggest industry, specifically a process called hydraulic fracturing or fracking.
Fracking blasts high-pressure water deep into the ground to release oil and natural gas.
"Fluids of all kinds, when they're injected underground, do, in some cases, induce small earthquakes," said Brian Stump, SMU Earth Sciences Professor.
Oklahoma geologist Austin Holland just finished a preliminary report that looked into whether fracking in the Eola Oil Field in Garvin County, could be connected to nearly 50 small earthquakes recorded near Elmore City last January.
His research found most of those tremors happened within 24-hours after fracking ended. While Holland says there is a "strong correlation," he also says it's "impossible to say with a high degree of certainty" whether those earthquakes were natural or man-made.
When it comes to Saturday's earthquakes - two of the strongest on record - he says the intensity of them and their location on a well-known fault line point to a force of nature.
"It would be quite a stretch to say this had been caused by man's actions. It's much, much more likely that these are naturally occurring earthquakes," Holland said.
Researchers have found that earthquakes linked to fracking are much smaller than the tremors seen in Oklahoma recently.
The National Academy of Sciences is expected to issue a report on fracking and seismic activity next year.