The U.S. Geological Survey (USGS) has released a first-ever map forecasting human-caused earthquake activity, as opposed to natural quakes. It affirms what people living near heavy oil and gas industry already know: Injecting industrial wastewater deep underground makes the Earth shake.
The USGS reports that the most significant hazards from so-called induced seismicity are in six states, listed in order from highest to lowest risk: Oklahoma, Kansas, Texas, Colorado, New Mexico and Arkansas. So far, though, Oklahoma tribes aren’t experiencing much shaking from earthquakes, and leaders surveyed by ICTMN expressed little concern.
“It hasn’t been a major concern yet that has been voiced to our department,” said Darren Shields, environmental director for the Kickapoo Tribe in central Oklahoma.
“I have felt two in the last eight years,” added Waddell Hearn, public relations director for the Choctaw Nation of Oklahoma. “It wasn’t a big deal at all.”
Still, Oklahoma and the Dallas-Ft. Worth area have emerged as areas most likely to see human-caused earthquakes over the next year; the USGS says seven million people there are at risk for near-term damage from earthquakes. Nearly 40 tribes call Oklahoma home—and their risk of damaging quakes now ranks among the highest in the country.
“Within a few areas of the central and eastern United States, the chances of damage from earthquakes, whether natural or induced, is similar to those of high-hazard areas in California,” said Mark Petersen, chief of the USGS National Seismic Hazard Mapping Project.
Petersen and his USGS study co-authors Michael Blanpied and Justin Rubinstein explained during a press call on Monday March 28 that Oklahoma has a history with very few earthquakes.
“Prior to 2010, we had one or two earthquakes per year,” Petersen said.
Oklahoma’s terrain is laced with dormant faults, and one of those in the southwestern part of the state, the Meers Fault, saw a magnitude 7 earthquake in prehistoric times. Earthquakes at and above magnitudes of 7 are considered to be the most serious, often leading to widespread damage.
“There has always has been a little bit of a threat there,” Petersen said. “Now that you have these very high, consistent levels of seismicity, the chance of having something larger has increased.”
The 2011 Prague earthquake, at a magnitude of 5.6, was the biggest one in recorded history and a case in point, he said.
The Oklahoma Corporation Commission, which regulates the oil and gas industry in Oklahoma, welcomed the USGS map as a good tool for justifying the sorts of sweeping new regulations the commission has been enacting in response to the earthquake swarms that started back in 2009, commission spokesperson Matt Skinner told ICTMN. The spate of quakes surprised regulators and industry executives alike. Since that time, Oklahoma has seen hundreds of earthquakes per year.
First Skinner’s agency pinned down the causes of earthquakes by looking at individual wells where wastewater from oil and gas operations had been re-injected underground. That practice—which occurs with or without fracking—is now known to be the culprit. Sometimes, he said, shutting off these re-injection wells would immediately halt a nearby earthquake in progress.
The early efforts also yielded information that has been helpful on a larger scale. For example, regulators learned that water sent too deep under the earth causes earthquakes, even though it was once viewed as good practice to save the quality of drinking water. So the commission’s first major regulatory action, in 2013, was to pull back about 300 of the state’s deepest re-injection wells.
The Commission has also been collecting data—with help from the USGS, the Oklahoma Geological Survey, academics and others—on links between earthquakes and wells that are high pressure and high volume. So far, the high-volume wells appear to present the greatest risks, and so the Commission’s latest action, in February and March of this year, has been to reduce wastewater disposal by 40 percent across two areas totaling 11,000 square miles. That’s the equivalent of a million barrels a day, and Skinner said it’s unclear how industry will deal with the reduction.
“Operators will have to figure out what to do with the water,” he said, adding that some may be able to take advantage of commercial disposal sites that have cropped up across the state. “When oil is at $100 a barrel, trucking it somewhere else is a greater possibility than it is when oil is $30 a barrel. It would be logical to assume that some operators will have to cut back on production.”
Skinner said there’s been little resistance from oil and gas producers, given the gravity of the earthquake problem. Hundreds of producers are affected, and although two companies, one large and one small, initially balked at the new restrictions, both have complied without turning to litigation.
The cutbacks will be phased in through the end of May to avoid rapid pressure changes underground, and Skinner says earthquakes are likely to continue in the short term. In fact, he said, he’d been awakened by two of them near Crescent, Oklahoma, on the morning of Tuesday March 29.
Despite the lack of immediate concern among Kickapoo tribal members, Shields said the tribe has a hazard mitigation plan approved by the Federal Emergency Management Agency. That plan ranks earthquakes as one of the top 10 natural threats facing the tribe, but tornado shelters are placed higher on the priority list. However, the new information is causing tribes to take a closer look.
“The hazard mitigation plan will be reviewed soon considering the new study from USGS on induced and natural earthquakes,” Shields said.