Kansans can expect more strong shaking after 5.8, 5.0 earthquakes

Kansans can expect more strong shaking following a series of large earthquakes in the region. A 5.8 magnitude earthquake centered near Pawnee, Oklahoma in September remains the largest in the region's history. Just two months later a 5.0 rocked the area and the U.S. Geological Survey expects the trend to continue.

"You're just wondering whether there's going to be another big one like that again," said John Green, a resident of Pawnee.

It's a new kind of fear for people in Oklahoma and across the border in Kansas.

Scientists say most earthquakes in this part of the country are triggered by the injection of water produced from oil wells. Gary LaRue, owner of a small oil company called PetroWarrior, doesn't deny that theory. But he says there are ways to reduce the quakes without shutting down wells across the region.

We visited LaRue at the well he operates about 30 miles from the epicenter of that 5.8 magnitude earthquake. He says only about 12 percent of the liquid coming out of his pump is oil. The rest is gas and a lot of saltwater that will eventually end up back underground.

"It's briny, salty. So it would kill anything you put it on the ground. You can't irrigate with it. It's got metals, heavy metals. So the best place for it is to put it back in the ground," said LaRue.

All of that water ends up going through a disposal well. LaRue estimates each of his disposal wells pump about 1,000 barrels of wastewater underground every day.

"We're not putting much down there but some guys are putting 30-40,000 barrels a day down one of these things. It would be millions of barrels a day across the state of Oklahoma," said LaRue.

LaRue says that's what's causing the earthquakes.

"Every body knows that's what it is. Every body in this business knows what's causing it," said LaRue.

But he believes there's a way to fix it - by setting tighter limits on the amount of water being disposed each day.

The Oklahoma Corporation Commission took action earlier this year, reducing the wastewater disposal in high-risk areas to no more than 15,000 barrels on average per day within a 30 day period.

Following the Pawnee earthquake, the OCC ordered dozens of disposal wells to shut down indefinitely. That affected half of LaRue's wells.

"Half my income is shut down right now," said LaRue.

That was before another 5.0 magnitude earthquake struck just a few miles from LaRue's injection well, forcing more to shut down in the area. LaRue says he'll have to cut back on wastewater injection, but has not been ordered to shut down any more wells.

Scientists with the US Geological Survey say it won't stop here. In 2016, the USGS gave southern Kansas and central Oklahoma a 10 percent chance of strong shaking. That percentage will increase following several five-plus magnitude quakes in the area. There's also a chance the earthquakes will get stronger. But pinpointing a time and place is impossible.

The Kansas Corporation Commission has taken action recently in regard to wastewater disposal. In 2015, the KCC reduced injection limits in parts of Sumner and Harper Counties to just 8,000 barrels a day.

In August of 2016, the KCC expanded restrictions, reducing other parts of Harper and Sumner Counties to 16,000 barrels a day. That order also included parts of Sedgwick, Kingman and Barber Counties.