Earthquake activity in Oklahoma has increased by around 4,000 percent over the past eight years, according to Carnegie Mellon University. Concerned about the dramatic rise, Carnegie Mellon and University of Pittsburgh researchers published two studies scrutinizing the connection between heightened seismic activity and wastewater injection into the earth after hydraulic fracturing, or fracking. Meanwhile, Oklahoma residents are suing 27 natural gas and oil companies over earthquake damage.

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Just in 2015, Oklahoma residents experienced 907 quakes with a magnitude of 3 or higher, up from 585 the year before and just 109 in 2013. A spike in earthquakes combined with what researchers call an impressive monitoring network afforded a prime opportunity to study the earthquakes. There are a couple of reasons why wastewater disposal after fracking might be causing all that seismic activity.

Related: USGS, EPA investigate link between underground wastewater disposal and Oklahoma’s largest earthquake

The report’s lead author, Pengyun Wang of Carnegie Mellon University, said fluid diffusion can reach stressed fault lines, which can slip and cause earthquakes. Or if the wastewater enters an underground reservoir close to a fault line, the new increased weight of the reservoir can stress those fault lines. Wang hoped their findings might be useful for both regulators and Oklahoma residents. He said, “If local residents of the area are experiencing the negative effects of increased seismicity and want to do something about it, without scientific evidence like this, these people might be powerless to argue against the owners of the wells. But if you can somehow give them evidence, I think it can improve overall awareness of the issue.” Bulletin of the Seismological Society of America published the studies online here and here.

Pawnee, Oklahoma citizens are taking the issue to court; they’re suing 27 natural gas and oil companies over earthquake damage. The beleaguered town has been racked with almost 800 earthquakes in a year. Many homes have been damaged, but insurance claims have been rejected because homeowners insurance doesn’t always include coverage for earthquakes. The lawsuit says the oil and gas companies have showed “reckless disregard for public or private safety.”

Just today, the United States Geological Survey reported yet another earthquake near Cushing, Oklahoma, that measured 4.0 on the Richter scale.

Via Phys.org and Grist

Images via OakleyOriginals on Flickr and Wikimedia Commons