Largest recorded Alberta earthquake not natural, from oilsands wastewater: study
The largest recorded earthquake in Alberta's history was not a natural event, but most likely caused by disposal of oilsands wastewater, new research has concluded.
"This event was caused by wastewater disposal," said Ryan Schultz, a Canadian seismologist who helped conduct the research while at Stanford University in California.
In November, parts of Alberta near the northwestern town of Peace River were rocked by a series of quakes culminating in one that reached a 5.6 magnitude.
Residents reported being knocked to their knees. The earth was pushed upward by more than three centimetres — enough to register on satellites.
Oilpatch techniques, such as deep disposal wells that inject wastewater kilometres underground, can induce earthquakes. One such well located near the earthquake site, used to dispose of water used in oilsands operations, has injected more than one million cubic metres of wastewater down about two kilometres.
After the record-breaking quake occurred, the Alberta Geological Survey, a branch of the province's energy regulator, attributed it to natural causes. The centre of the quake, then estimated to be six kilometres underground, was thought too deep and too far away from oilpatch activity in time and space to have been generated by industry.
Not so, said Schultz.
A closer and more thorough look at the data brought the centre of the quake up to about four kilometres beneath the surface. That figure is now reflected in the regulator's catalogue of Alberta quakes.
Similarly, a look at previous research on so-called "induced seismicity" revealed long lag times between deep-well water injection and earthquakes.
A previous disposal site in Alberta started quaking three years after pumping began, Schultz said. A Dutch disposal well didn't start causing earthquakes for decades.
As well, history shows deep water disposal can cause earthquakes up to 20 kilometres away. Alberta's November earthquakes were nowhere near that distant.
"The clusters of earthquakes were right on top of a deep disposal well," Schultz said.
His paper, co-authored by scientists at the University of Alberta as well as Natural Resources Canada and published in Geophysical Research Letters, suggests that the injected water forced itself between the two sides of a fault deep in the earth. That water was enough to reduce the friction holding the two sides together and eventually resulted in a slippage that shook the surface.
Statistical analysis of correlation between the quakes and the underground pumping was conclusive, Schultz said.
"We had a confidence somewhere between 89 and 97 per cent just in the timing," he said. "There is enough information to start making these kinds of links."
Schultz said the findings could have big implications for Canada's and Alberta's climate change plans.
Both jurisdictions favour reducing the climate impact of the province's energy industry by pumping vast amounts of waste carbon dioxide deep underground, much as wastewater is injected. So-called carbon capture and storage could have the same seismic effects as deep wastewater disposal, Schultz said.
"If carbon capture is going to be done at a scale that is going to combat climate change, then significant amounts of volume need to be put in the ground," he said. "You might expect then also getting these types of earthquakes the more volume that you store."
That doesn't necessarily mean carbon capture and storage is a bad idea, he said, but it means a lot more seismic monitoring needs to take place around the sites to keep track of what's happening deep in the earth.
"This could be an issue," Schultz said. "Monitoring will tell.
"You need to be able to see what is going on."
This report by The Canadian Press was first published March 23, 2023.
CTVNews.ca Top Stories
NEW Keeping these exotic pets is 'cruel' and 'dangerous,' Canadian animal advocates say
Canadian pet owners are finding companionship beyond dogs and cats. Tigers, alligators, scorpions and tarantulas are among some of the exotic pets they are keeping in private homes, which pose risks to public safety and animal welfare, advocates say.
NEW Life got in the way of one woman's reunion with her father, but a DNA test gained her a family
Anne Marie Cavner was the closest she'd ever been to meeting her biological father, but then life dealt her a blow. From an unexpected loss to a host of new relationships, a DNA test changed her life, and she doesn't regret a thing.
Doctors ask Liberal government to reconsider capital gains tax change
The Canadian Medical Association is asking the federal government to reconsider its proposed changes to capital gains taxation, arguing it will affect doctors' retirement savings.
Quebec farmers have been protesting since December. Is anyone listening?
Upset about high interest rates, growing paperwork and heavy regulatory burdens, protesting farmers have become a familiar sight across Quebec since December.
'Catch-and-kill' strategy to be a focus as testimony resumes in Trump hush money case
A veteran tabloid publisher was expected to return to the witness stand Tuesday in Donald Trump's historic hush money trial.
Quebec Health Department reports 28 cases of eye damage linked to solar eclipse
Quebec's Health Department says it has received 28 reports of eye damage related to the April 8 total solar eclipse that passed over southern parts of the province.
Psychologist becomes first person in Peru to die by euthanasia after fighting in court for years
A Peruvian psychologist who suffered from an incurable disease that weakened her muscles and had her confined to her bed for several years, died by euthanasia, her lawyer said Monday, becoming the first person in the country to obtain the right to die with medical assistance.
Diver pinned under water by an alligator figured he had choice. Lose his arm or lose his life
An alligator attacked a diver on April 15 as he surfaced from his dive, nearly out of air. His tank emptied with the gator's jaws crushing the arm he put up in defence.
How quietly promised law changes in the 2024 federal budget could impact your day-to-day life
The 2024 federal budget released last week includes numerous big spending promises that have garnered headlines. But, tucked into the 416-page document are also series of smaller items, such as promising to amend the law regarding infant formula and to force banks to label government rebates, that you may have missed.