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
BREAKING Ontario Provincial Police arrest 64 suspects in child sexual exploitation investigation
Ontario Provincial Police say 64 suspects are facing a combined 348 charges in connection with a series of child sexual exploitation investigations that spanned the province.
AstraZeneca says it will withdraw COVID-19 vaccine globally as demand dips
AstraZeneca said on Tuesday it had initiated the worldwide withdrawal of its COVID-19 vaccine due to a 'surplus of available updated vaccines' since the pandemic.
Toronto police seek suspect vehicle after security guard shot outside Drake's mansion
Toronto police are seeking help from the public as they continue to investigate a shooting that seriously injured a security guard outside rapper Drake's mansion.
World's record-breaking hot temperature streak stretches through April
The world just experienced its hottest April on record, extending an 11-month streak in which every month set a temperature record, the European Union's climate change monitoring service said on Wednesday.
Most of Canada to receive emergency alert test today
The federal government will test its capacity to issue emergency alerts today, with the exception of Ontario, where the test will take place on May 15.
OPINION What King Charles' schedule being too 'full' to accommodate son suggests
Prince Harry, the Duke of Sussex, has made headlines with his recent arrival in the U.K., this time to celebrate all things Invictus. But upon the prince landing in the U.K., we have already had confirmation that King Charles III won't have time to see his youngest son during his brief visit.
Seafood, eat food: Calgary Stampede releases Midway menu
The Calgary Stampede has released its menu of sweet, salty and spicy treats available on the Midway for the Greatest Outdoor Show on Earth.
Boy Scouts of America is rebranding. Here's why they've changed their name
After more than a century, Boy Scouts of America is rebranding as Scouting America, another major shakeup for an organization that once proudly resisted change.
Ontario man devastated to learn $150,000 line of credit isn't insured after wife dies
An Ontario man found out that a line of credit he thought was insured actually isn't after his wife of 50 years died.