Study: Wastewater Disposal Triggered Earthquake
New research from Stanford University suggests that one of the most powerful earthquakes ever recorded in Alberta, Canada, was caused by wastewater injected underground by oil and gas operators.
The study was recently published in the journal Geophysical Research Letters, reportedly making it the first study to link seismicity in the area to human activity.
About the Study
On Nov. 30, 2022, a 5.6-magnitude earthquake occurred in northwestern Alberta. While residents felt shaking more than 400 miles away, there were no reported injuries or damage. Three slightly smaller earthquakes struck the same area again on March 16.
The Alberta Geological Survey, a branch of the Alberta Energy Regulator, described the earthquake as a natural tectonic event at the time. However, the new analysis from Stanford geophysicists suggests that the disposal of wastewater deep underground by the oil industry most likely triggered the tremor.
“Earthquakes of similar magnitude to the Peace River event could be damaging, even deadly, if they happened in more populated areas,” said study lead author Ryan Schultz, who recently completed his Ph.D. in geophysics at the Stanford Doerr School of Sustainability. “It is important that we understand the mechanics involved and how to avoid inducing more of these events.”
A new study by Stanford University researchers has found that one of the most powerful earthquakes ever recorded in Alberta, Canada, was likely caused by oil and gas activity. https://t.co/AhsVeZzGwb— Stanford Doerr School of Sustainability (@stanforddoerr) March 27, 2023
“The Peace River earthquake caught our interest because it occurred in an unusual place,” said co-author William Ellsworth, a research professor of geophysics and co-director of the Stanford Center for Induced and Triggered Seismicity. “Multiple lines of compelling evidence point to this quake as being man-made.”
Stanford reports that the team employed an approach that considers seismic events’ details and context to assess the earthquake’s origins, including location, depth, timing, regional history of background earthquakes, and records of industrial activity.
Operations in the Peace River area include extracting a form of oil known as bitumen. Workers must inject huge amounts of hot water or solvents underground to mobilize the tar-like substance for easier pumping up to the surface.
This consequently produces water mixed with heavy metals, hydrocarbons and harmful chemicals that is disposed of by re-injecting it underground. According to the study, since bitumen recovery operations began in the Peace River study area in the 1980s, about 40,000 Olympic swimming pools (100 million cubic meters) of wastewater have been injected underground.
Then, researchers compared publicly available information about wastewater disposal activities in the Peace River area to ground deformation measured by satellite and regional seismic monitors. Overall, Stanford reports, the results tied frequent, minor earthquakes to wastewater disposal from bitumen recovery going back almost a decade.
In terms of the November 2022 quake, satellite observations reportedly showed a dramatic 3.4-centimeter uplift in the ground. This elevation change reportedly proved consistent with seismic movement along a previously undocumented fault line. As a result, the study claims that the high volume of disposed wastewater had increased water pressure on the fault, weakened it and made it prone to slip.
Schultz described the Peace River quake as a “cautionary tale” for a region where government and industry aim to expand hydrogen production and carbon capture and storage in the coming years while continuing oil-sands wastewater disposal.
According to the university, one proposed approach to producing hydrogen involves splitting natural gas into hydrogen and carbon dioxide, then capturing the CO2 and compressing it into a supercritical fluid for long-term storage.
“Switching to ‘blue’ hydrogen will require disposal by injection of unprecedented volumes of supercritical carbon dioxide,” said Schultz. However, like the wastewater from bitumen production, injecting carbon dioxide underground could trigger seismicity, he added.
The Stanford researchers hope that expanding seismic monitoring in active petroleum recovery sites will help scientists better understand when and how human activity leads to earthquakes.
“It is vitally important that we understand all aspects of induced seismicity, from basic physical mechanisms to risk management,” said Ellsworth.
Stanford co-authors also included geophysics postdoctoral scholar Jeong-Ung Woo; Karissa Pepin, Ph.D.; Howard Zebker, professor of electrical engineering and of geophysics; and Paul Segall, the Cecil H. and Ida M. Green Professor of Geophysics. Additional co-authors are affiliated with University of Alberta, Edmonton, and Natural Resources Canada.
This research was supported by the Stanford Center for Induced and Triggered Seismicity.