“In a typical year prior to 2013, we might have picked up one, two, three earthquakes,” said Rex Buchanan, interim director of the Kansas Geological Survey at the University of Kansas. “Obviously we’ve outdone that dramatically.”
All of the state’s earthquakes over the past stretch occurred in just two southern counties that run along the Kansas-Oklahoma border, raising questions about the quakes’ ties to hydraulic fracking in the region – although industry disputes the connection.
During the fracking process, a mixture of saltwater, sand and chemicals is blasted into the ground, breaking up rock formations to release oil and natural gas.
In 2000, there were just under 2,000 permitted wells in Kansas. By 2014, that number had grown to more than 7,000.
Fracking has been going on in Kansas since the 1940s, but the recent innovation of horizontal drilling – instead of vertical – requires more water. The wastewater is injected into disposal wells – “not exactly where it came from,” Buchanan said. He added that the earthquakes are likely being caused by the wastewater disposal wells, not the act of drilling itself.
“In Kansas, you produce a lot more saltwater than you do oil in the oil and gas production process,” Buchanan said. “We’re dealing with much greater volumes of water than ten years ago.”
A 2015 study from Stanford researchers came to similar conclusions. The study found that a spike in earthquakes in Oklahoma was caused by wastewater disposal wells, not drilling.
After a comparatively quiet summer, seismic events have picked back up in south-central Kansas. The largest quake over the past weeks occurred near the town of Caldwell in Sumner County where, on Oct. 27, there was a 3.6 magnitude earthquake.
In that same time period, there were just 11 earthquakes in the bordering counties to the south in Oklahoma.
Buchanan, who served on an earthquake task force appointed by Kansas Governor Sam Brownback, testified to state legislative committees earlier this year about fracking and earthquakes. In March, the Kansas Corporation Commission, the state agency that regulates the oil and gas industry, ordered hydraulic fracking operators in Harper and Sumner counties to reduce the amount of wastewater injected into disposal wells.
It is too early to tell if that move has any impact on the frequency of the earthquakes, Buchanan said.
“Linking a specific disposal well to a specific earthquake is very difficult,” Buchanan said. “Certainly we’ve got big disposal wells on our side of the border, and there are big disposal wells on the Oklahoma side. Finding how much influence with what’s happening in Oklahoma in terms of seismicity in Kansas, and vise versa, has been a challenge.”
Indeed, one representative of the industry challenged the proposed linkage.
“The likelihood that induced seismic events will occur in properly permitted and operated [disposal wells] is very small,” Edward Cross, president of the Kansas Independent Oil & Gas Association, said in an e-mailed statement. “Too often, the mere presence of nearby oil and gas wells or [disposal] wells results in allegations that they are the source.”
Cross added that seismic activity fluctuates naturally, and that it is too soon to tell if there is a relationship between wastewater disposal and seismic activity.
Tiffany Hartson, city clerk for the town of Harper, said she hadn’t felt any of the earthquakes this week, but that residents have noticed the increase over the past few years.
“A lot of people went out and got earthquake insurance they didn’t have before,” Hartson said. “It’s not really the topic of conversation. I don’t know if it’s because we’ve become so used to it, or what.”