Scientists struggle to figure out why ground is shaking in heartland
07/03/2014 4:03 PM
07/05/2014 4:15 PM
Months after the prairie began to shake, scientists still struggle to explain a surge in Kansas earthquakes that appears connected to increased fracking.
The Kansas quakes are part of a major escalation in earthquakes that have struck the nation’s heartland in the wake of the oil and gas boom. The epidemic has hit places in Texas and especially Oklahoma where earthquakes used to almost never happen, with scientists increasingly pointing the finger at deep underground injection of drilling waste that effectively lubricates and weakens fault lines.
Kansas Gov. Sam Brownback appointed a task force in February to study the earthquakes in his state and the U.S. Geological Survey started investigating. But the task force is moving slowly and the USGS is lacking information on the area’s oil and gas activity.
The Kansas Corporation Commission, the state agency that regulates oil and gas, collects wastewater injection data once a year, in March, said Justin Rubinstein, a geophysicist with the U.S. Geological Survey who has been working on the mystery prairie quakes.
“Unless we get the data sooner it will be very difficult to say anything about whether there is any connection from wastewater wells to the earthquakes until next March,” he said.
Rubinstein said potential causes for the quakes include the wastewater injection wells, the fracking process itself, or simply the hand of nature.
“Everything is still on the table at this point,” he said.
There is circumstantial evidence, including the fact that the Kansas earthquake surge corresponds to increased oil and gas activity in the area.
There’s also the fact that scientists have already linked deep injection of drilling waste to earthquakes just over the border in Oklahoma, which is seeing a massive spike in seismic activity. Oklahoma experienced 145 earthquakes greater than 3.0 magnitude between January and May. That compares to a state long term average that used to be just two such quakes in an entire year.
“There have been a number of papers that have indicated at least a majority of these earthquakes appear to be induced. They appear to be related to wastewater injection,” Rubinstein said.
Scientists warn that the shaking could get stronger. The USGS and the Oklahoma Geological Survey said the intense seismic activity is increasing the likelihood that Central Oklahoma is going to experience damaging earthquakes of greater than 5.5. magnitude.
Bill Leith, senior earthquake science adviser at USGS, said the warning should “become a crucial consideration in earthquake preparedness for residents, schools and businesses in the area.” More than 500 people in Oklahoma recently packed a meeting looking for answers.
Kansas experienced 56 earthquakes between October and April, most occurred in the south central area of the state. The quakes are big enough to feel and the largest, about a 3.9 magnitude, led to reports of cracked walls and rattling furniture in Sumner and Harper counties.
The governor announced a seismic task force in February as a “matter of public safety.” The task force is creating an action plan but is being slowed by the resignation of one of its three members, said Rex Buchanan, a member and the interim director of the Kansas Geological Survey.
Buchanan said the task force has not spent a lot of time discussing whether the oil and gas injection wells are responsible for the earthquakes.
The number of earthquakes has dropped off in recent months, he said, and conversations about the cause of them dwindled. The task force is waiting for the USGS seismic findings that might shed light on whether drilling waste injection wells are responsible, he said.
USGS researcher Rubinstein said a drop in quakes doesn’t mean the problem is over or that it is not caused by oil and gas activity. He said it’s normal for the numbers to go up and down, whether the earthquakes are natural or induced by injection of drilling waste.
“Certainly we see the number bouncing up and down in Oklahoma, where we think a good percentage of the earthquakes are induced,” Rubinstein said.
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