A number of seismologists have concluded that the 5.7-magnitude earthquake that hit near Prague a year and a half ago was caused by injecting wastewater from oil and gas production deep underground.
Earthquakes in other states have been linked to disposal wells, but Oklahoma’s is the largest. Yet Oklahoma’s regulatory response has been one of the smallest.
Seismologists have linked wastewater disposal wells to earthquakes in at least a half-dozen states. On a geologic scale, the tremors are small. And the quakes — in states like Arkansas, Colorado, Illinois, and Ohio — have all been smaller than the November 2011 quake that shook Oklahoma near Prague.
But regulatory response in those states has been greater. Oklahoma Corporation Commissioner Matt Skinner says that’s because there’s no real consensus.
“There is suspicion on the part of researchers — some researchers — that induced seismicity, that this is the result of oil and gas production,” Skinner says. “And we also have the researchers who say, thus far, all the data shows no evidence of induced seismicity.”
In March, the geoscience journal Geology published a study that concluded Oklahoma’s quake was likely triggered by wastewater disposal wells used by the oil and gas industry.
But Oklahoma’s oil and gas regulator relies on analysis from the state’s official seismologist — Austin Holland at the Oklahoma Geological Survey. He says the data point to natural causes. No new rules or laws addressing manmade earthquakes have been proposed in Oklahoma, but the Corporation Commission is considering guidelines for the oil and gas industry.
Holland is drafting some recommendations that might be used. They are likely to be finalized this fall. He says the oil and gas industry and regulators can use the guidelines to effectively monitor, mitigate the risk, and respond in situations that may come up.
These guidelines are totally voluntary, but actual rules or laws with teeth in them are the sort of thing that industry often opposes. Rules haven’t been ruled out, Skinner says. But right now, Oklahoma is eying voluntary ways to reduce the risk.
“We recognize there is a need for formalized guidance, and that’s what we’re working towards,” Skinner says.
The response in other states has been tougher. After a series of quakes peaked with a magnitude-4 tremor near Youngstown, Ohio regulators there responded by banning disposal wells in risky areas. Arkansas did something similar after a swarm of quakes shook the state in 2010 and 2011. In Colorado, permits for disposal wells must be reviewed by state seismologists. Lawmakers in Illinois are considering a “traffic light” system that allows authorities match their response with earthquake intensity.
More than a dozen researchers at the National Academy of Sciences proposed the traffic light system in a report released last year. The academy identified other risk factors, like active disposals wells located near fault lines.
“It’s no mystery that you increase the chance of triggering seismicity if you’re injecting near a fault,” Holland says.
So what about the Wilzetta Fault that produced Oklahoma’s 5.7-magnitude quake that injured two people and destroyed 14 homes? The fault line surrounded by disposal wells that four seismologists say were the likely culprit? Skinner says injection still takes place near Prague, but Holland deflected a questions as to whether or not he’d recommend injecting near the fault line as best practices.
StateImpact is a collaboration of Oklahoma’s public media stations and NPR, examining how government affects people’s lives.