Colorado regulators halted the disposal of fracking wastewater into a well this week after a small earthquake was detected in the area around the well.
As Reuters reports, High Sierra Water Services will stop pumping wastewater into a well in Weld County, CO for 20 days, on orders from the Colorado Oil and Gas Conservation Commission (COGCC). The halt comes as a precaution after University of Colorado seismologists detected a 2.6-magnitude earthquake in the region Monday, the second earthquake to hit the area in the last month — on May 31, a 3.4-magnitude earthquake was also detected in the region.
During the 20-day period that wastewater injection is halted, the COGCC will try to determine whether the earthquake can be tied to wastewater injection activity.
“In light of the findings of CU’s team, we think it’s important we review additional data, bring in additional expertise and closely review the history of injection at this site in order to more fully understand any potential link to seismicity and use of this disposal well,” COGCC Director Matt Lepore said.
If the earthquake does end up being tied to wastewater injection, it would likely be the first time that has happened in the state, a COGCC spokesman told Reuters.
But it wouldn’t be the first time the practice has been tied to earthquakes in other parts of the United States. To dispose of their wastewater — which often contains carcinogens and other toxic substances — fracking companies inject the water deep into underground wells. This wastewater can make it easier for faults, which otherwise are able to take high levels of stress, to slip. According to the U.S. Geological Survey, injected wastewater “counteracts the frictional forces on faults and, in effect, ‘pries them apart,’ thereby facilitating earthquake slip.” That’s why the USGS lists wastewater injection as a potential trigger for earthquakes.
That link has been confirmed multiple times in recent years. In 2012, oil and gas regulators in Ohio said a string of 12 earthquakes in the Youngstown, Ohio area was likely triggered by wastewater injection. Before 2011, Youngstown hadn’t experienced an earthquake since records began in 1776. But in the year after fracking companies began pumping their wastewater underground in the region in December 2010, Youngstown seismometers recorded 109 earthquakes.
Oklahoma, too, has experienced an uptick of earthquakes in recent years, leaving many residents wondering whether wastewater injection has played a role in their state’s seismic activity. Over just 30 days in March and April, Oklahoma experienced 133 2.5-magnitude or greater earthquakes — more than all of last year combined. Before 2009, Oklahoma experienced no more than three 3.0 or higher earthquakes a year, but as fracking wastewater injection has risen since the beginning of 2009, so has the number of earthquakes.
Researchers in Texas have also tied earthquakes in the Fort Worth Basin to wastewater injection. Residents of some Texas towns have called on fracking companies to halt their wastewater injection — Azle, Texas, for instance, experienced 30 quakes in the span of three months at the end of 2013 and beginning of 2014, a spate of earthquakes that worried residents.
“They haven’t had earthquakes around here for 100 years, and to have this happen now — 32 within just the last couple of months — is crazy,” Darla Hobbs, an Azle resident, said in January. “And it’s not our fault for living here. It’s the gas well industry for drilling, and fracking, and the injection wells.”
More recently, geologists have for the first time tied the process of fracking itself — the injection of water, sand, and chemicals underground to unlock oil and gas stores — to earthquakes in Ohio.