Study finds wastewater disposal from oil activity triggered major earthquake in Canada

Formerly, researchers have linked earthquakes to fracking and wastewater disposal in parts of Alberta and British Columbia. However, the new study, published March 23 in Geophysical Research Letters, is the first to link "such a large earthquake to human activities this far away from the mountain range, in a region where industry centers on exploiting oil sands rather than fracking for natural gas," a press release said.

Solid evidence of a man-made earthquake

"Earthquakes of similar magnitude to the Peace River event could be damaging, even deadly, if they happened in more populated areas," study lead author Ryan Schultz, who recently completed his Ph.D. in geophysics at the Stanford Doerr School of Sustainability, said in a statement.

"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."

Bitumen extraction is rife in the Peace River area center. Workers inject massive amounts of hot water or solvents underground to mobilize the substance akin to tar, which mixes with heavy metals, hydrocarbons, and harmful chemicals. How can this wastewater be disposed of? By re-injecting it underground.

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.

Information about wastewater disposal activities in Peace River to ground deformation measured by satellite and regional seismic monitors was publicly available. When the researchers poured through data, they found that the results tied frequent, minor earthquakes to wastewater disposal from bitumen recovery going back almost a decade, "strongly implicating" the big November 2022 tremor.

Satellite data revealed the final nail in the coffin

A significant piece of evidence was revealed through satellite observations. They showed a 3.4-centimeter uplift in the ground during the November quake. "This elevation change proved consistent with seismic movement along a previously undocumented fault line. According to the study, the high volume of disposed of wastewater had increased water pressure on the fault, weakened it, and made it prone to slip," the release states.

The results are imperative to avoid inducing more of these events. They also have safety implications for ongoing and future energy-related operations, such as the underground storage of carbon dioxide to help mitigate climate change.

According to Stanford researchers, expanding seismic monitoring in active petroleum recovery sites in Peace River and elsewhere will help scientists better understand when and how human activity leads to earthquakes.