As dawn broke this morning, Oklahoma was hit with another powerful earthquake. This quake, with a 5.0 magnitude, is one of 28 other earthquakes in the past week, and 2,200 earthquakes in the past year, according to Earthquake Track.
And they're no longer a huge surprise. After a 5.1-magnitude earthquake hit Oklahoma this February, residents were left scrambling for answers to the deadly and rare event, and scientists seem to be zeroing in on the answer: the wastewater that occurs after fracking.
Researchers at the U.S. Geological Survey suspect that hydraulic fracturing, a process in which water is used to remove oil from rocks deep underground, was behind this powerful earthquake. It turns out the the disposal method of the water used in fracking was likely the cause of the third largest earthquake in Oklahoma's history, according to the USGS.
A study from the USGS released this fall indicates the practice of pumping fracking wastewater deep into underground rock caused the earthquake.
The U.S. Environmental Protection Agency estimates about two billion gallons of brine are injected into rocks every day, 20 percent of which are used exclusively for disposing of the water. Most of them are in Oklahoma, Texas, California and Kansas.
But here's the twist: the wastewater injection sites blamed for the quake were about seven miles away, meaning wastewater disposal sites from fracking operations can cause disruptions along fault lines far from the sites themselves.
The fact that the tremors weren't very strong near the wastewater wells, but very strong miles away, means researchers don't know all there is to know about how these injection sites can affect surrounding areas, said Dr. William Yeck, a USGS scientist and lead author of the study, in an announcement of the findings.
The 5.1-magnitude earthquake occurred along a fault line near Fairview, Oklahoma, the strongest earthquake in the state since a 5.7-magnitude quake hit Prague, Oklahoma. The relationship between the Prague earthquake and wastewater disposal is still under investigation.
The USGS has warned previously that wastewater disposal can induce earthquakes along fault lines. They also note that not all fracking wastewater disposal causes earthquakes, and fracking isn't the only operation that produces and disposes of wastewater within rocks.
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