A 5.6-magnitude earthquake hit the remote Peace River region in northeastern Alberta, part of Canada’s oil sands sector, on November 30, 2022. Although feeling shaking more than 400 miles away, no injuries or damage have been reported by residents or businesses.
The earthquake was described as a natural tectonic event by energy regulators. However, a rigorous new analysis by Stanford geophysicists suggests that oil industry activity – specifically, wastewater disposal deep underground – most likely triggered the tremor. Three slightly smaller earthquakes struck the same area again on March 16, less than a mile from last year’s big quake.
In other sections of Alberta and British Columbia, which straddle the Canadian Rocky Mountains, researchers have long linked earthquakes to fracking and wastewater disposal. This is the first study to relate such a significant earthquake to human activity so far away from the mountain range, where the industry is focused on oil sand extraction rather than fracking for natural gas.
The findings have safety implications for current and future energy-related operations, such as underground carbon dioxide storage to help migrate climate change.
Study lead author Ryan Schultz, who recently completed his Ph.D. in geophysics at the Stanford Doerr School of Sustainability, said, “Earthquakes of similar magnitude to the Peace River event could be damaging, even deadly if they happened in more populated areas. It is important that we understand the mechanics involved and how to avoid inducing more of these events.”
Co-author William Ellsworth, a research professor of geophysics and co-director of the Stanford Center for Induced and Triggered Seismicity, said, “The Peace River earthquake caught our interest because it occurred in an unusual place. Multiple lines of compelling evidence point to this quake as being man-made.”
Scientists have confirmed hundreds of earthquakes caused by oil and gas operations around the world, particularly in the United States, in recent decades.
To examine the origins of the Peace River earthquake, Stanford researchers and colleagues used a well-proven approach that considers seismic event details and context, such as location, depth, time, regional history of background earthquakes, and records of industrial activity.
The extraction of bitumen, a thick, black, sticky oil, is the focus of operations in the Peace River area. Workers inject huge quantities of hot water or solvents underground to mobilize the tar-like substance for easy pumping up to the surface, where it can mix with heavy metals, hydrocarbons, and harmful chemicals.
The most cost-effective method of disposing of this wastewater is to re-inject it underground. Approximately 40,000 Olympic swimming pools (100 million cubic meters) of wastewater have been pumped underground since bitumen recovery efforts began in the Peace River study region in the 1980s.
They compared publicly available data on wastewater disposal in Peace River to ground deformation observed by satellites and regional seismic monitors.
Ellsworth said, “The Alberta government deserves credit for its transparency in providing public access to production and disposal data.”
According to the study, At the time of the November quake, satellite observations showed a dramatic 3.4-centimeter uplift in the ground. The 2022 Peace River earthquake is a cautionary tale for a region where the government and industry aim to increase hydrogen production and carbon capture and storage. The high volume of disposed wastewater increased water pressure on the fault, weakened it, and made it prone to slip.
According to Schultz, The 2022 Peace River earthquake is “a cautionary tale” for a region where government and industry plan to increase hydrogen production and carbon capture and storage in the coming years while continuing to dispose of oil sands wastewater.
One proposed method for producing hydrogen is to split natural gas into hydrogen and carbon dioxide, then capture and compress the CO2 into a supercritical fluid for long-term storage.
The Stanford researchers believe that expanding seismic monitoring in active petroleum recovery sites, such as Peace River, will help scientists better understand when and how human activity causes earthquakes.
Ellsworth said, “It is critical that we understand all aspects of induced seismicity, from basic physical mechanisms to risk management.”
The Stanford Center for Induced and Triggered Seismicity funded the study.
The results of the study linked regular, minor earthquakes to wastewater discharge from bitumen recovery going back nearly a decade, strongly suggesting the large November 2022 quake as well.