In 2011, the town of Trinidad quivered from the seismic waves of a 5.3-magnitude earthquake. Located just 15 miles north of the quake’s epicenter in the Raton Basin, Trinidad sustained minor damage to buildings and structures.
Though historically rare in Colorado, this earthquake was just one in an ongoing series of earthquakes scientists say are being caused by injecting wastewater into underground formations in the area. The wastewater is produced during coal-bed methane extraction.
While scientists have studied the oil and gas industry’s role in causing such earthquakes for years — the earlist quake/injection well studies began in the 1960s — new research from the University of Colorado Boulder provides more specific information about how injecting fluids actually triggers the earthquakes, and raises concerns about the future of this long-held industry practice.
The Raton Basin stretches across the Colorado-New Mexico border and has long yielded resources like coal and coal-bed methane. It is home to 28 wastewater injection wells.
Although reports on the Basin show a history of seismicity, the rate of earthquakes dramatically increased starting in 2001. From 2008-2010, the Basin experienced the highest number of earthquakes in both states: 1,881 overall.
Wastewater injections — which began in the area in 1994 — also increased during this period, leading scientists to conclude that faster water buildup triggers more earthquakes. Since the first injection, oil and gas companies have pumped at least 200 million barrels of wastewater into underground formations in the area.
While a 2014 paper by the Geological Service charged injection wells with causing the area’s earthquakes, the recent CU study explains exactly why the Basin has become a prime location for this geological phenomenon.
Hydrogeologic modeling allowed researchers to find elevated pore pressure in the Raton Basin’s “basement rock” — a layer of rock miles deeper than the surface-level sedimentary layers where fracking occurs. Pore pressure is the fluid pressure between rock fractures and pores, and builds up over time as more and more wastewater enters the area. Since basement rock is typically more fragile and brittle than other rock layers, it should come as no surprise that a buildup of pore pressure could cause earthquakes in this vulnerable rock.
The study also uncovered the existence of two major faults in the Basin — the Vermejo Park fault and the Tercio fault. According to Shemin Ge, Geological Sciences department chair at CU, the 2008-2010 earthquakes observed in the study helped scientists locate the faults.
“We didn’t know about them before, but the earthquakes [lit] them up and brought them to life,” she says.
Knowledge of such faults contributes to a better understanding of the area and the nature of induced earthquakes. But when it comes to learning more about the Raton Basin and wastewater injection practices, scientists find themselves on the outside of an arena dominated by oil and gas companies.
Although the oil and gas industry has been monitoring seismic activity and subterranean faults in the Raton Basin for years, it will not make its data available to researchers or the public.
Jenny Nakai, CU doctoral student and lead author of the study, wishes the industry would be more willing to cooperate with researchers.
“If they had a map of basement faults, researchers would really love that because it would make our work so much easier,” she says.
Another complication stems from doubt and scrutiny centered on studies like this one. According to Ge, oil and gas industry members, as well as the general public, are often slow to accept the results of such studies. Although the Raton Basin saw an increase in seismic activity in 2001 — just a few years after the inception of wastewater wells in the area — the concept of induced seismicity was highly contentious until the 2014 Geological Service’s study.
“Even five years ago, not everyone was on board [with induced seismicity]. It was quite debated,” Ge says. “But now, because of these studies, there is a general consensus.”
Still, doubts remain. The Colorado Oil and Gas Association (COGA) is still reviewing the CU study and points to U.S. Geological Survey data that indicates the majority of injection wells — 98.8 percent — operate without seismicity.
Operators are required “to submit detailed documentation on the geology where they plan to drill or inject water prior to receiving a permit,” COGA CEO Dan Haley says in a statement to Boulder Weekly.
COGA is not alone in its opposition. Energy In Depth, an online publication founded by the Independent Petroleum Association of America, called the study “old news” and questioned the existence of any real scientific breakthroughs. “Is this a groundbreaking study? No, not really,” the article reads.
The CU Boulder researchers disagree, but they aren’t surprised by such comments.
“This is a complex issue. There’s economy, natural resources and hazards, social responsibility and the environment,” Ge says. “We think it’s important to understand the science behind it, but everyone in the industry needs to have an understanding.”
As for the future of the Raton Basin, more earthquakes are certainly possible. Unfortunately, it’s impossible, to fully predict when the next one will strike, an uncertainty that Nakai says knocks on the industry’s door. She believes the industry has a responsibility to work more closely with the academic community in order to educate people who live in the area.
“It’s pretty reasonable to assume that a fault in that basin is capable of producing another 5.3,” she says. “If people are going to have earthquakes nearby, they should know something about earthquake preparedness.”
But mere preparedness might not be enough. Ge believes that oil and gas companies should decrease the amount of wastewater being injected into the Earth. But given our demand for energy and an unwillingness to embrace alternatives, she does not anticipate that the practice will end anytime soon. Scientists may struggle to uncover the full scope of environmental impacts unless the oil and gas industry decides to cooperate.
“Ideally the companies should minimize any negative impact, but completely stopping energy development is probably not a practical approach,” Ge says. “How we can do it responsibly — and that’s protecting the environment, minimizing any harmful impacts and hazards — that’s something we’d like to contribute to.”