A megathrust earthquake hit South Vancouver Island 320 years ago on Jan. 26, 1700. While scientists encourage preparation, they say the 320-year mark doesn’t mean another earthquake is necessarily imminent. (Black Press File Photo)

A megathrust earthquake hit South Vancouver Island 320 years ago on Jan. 26, 1700. While scientists encourage preparation, they say the 320-year mark doesn’t mean another earthquake is necessarily imminent. (Black Press File Photo)

320 years since the ‘Big One’ doesn’t mean it’s overdue: B.C. professor

‘It could happen today, tomorrow or 100 years from now’

Next month marks 320 years since the Cascadia Megathrust earthquake rocked the B.C. coast, shooting a tsunami wave at the speed of a jumbo jet across the Pacific Ocean to Japan.

The impact was recorded overseas and left a historically viable marker of what was likely one of the most catastrophic natural events in region’s history.

READ ALSO: POLL: When do you think the next major earthquake will hit Vancouver Island?

READ ALSO: B.C. has history of big earthquakes

While the threat of the ‘Big One’ is a quiet source of concern for many – a looming, abstract dread behind calls for seismic infrastructure upgrades, earthquake safety awareness and regular ‘ShakeOuts’ in schools and offices across the region – the next megathrust is not necessarily overdue.

“We can’t predict earthquakes and we are a million miles away from being able to,” says Edwin Nissen, University of Victoria professor and Canada Research Chair in geophysics. Nissen has expertise in global geohazards including the subduction zones of the Cascadia plate boundary – the convergent boundary stretching from northern Vancouver Island to northern California.

“It’s wrong to say the next earthquake is overdue,” he says – pointing to the unpredictable pattern of plate shifts over history. “But it is correct to say it might happen tomorrow. It might happen today or tomorrow or in 100 years.”

READ ALSO: Be Prepared: Hospitals prep for mass casualties

The factors behind the next big quake are complicated, but boil down to the Cascadia subduction zone, where the oceanic plate is pushed below the continental lithosphere. Typically, the plates are stuck in that position, but when the oceanic plate slides deeper beneath the continental plate, an earthquake – and tsunami– is generated.

The estimated time between Cascadia subduction zone earthquakes is anywhere from 200 to 800 years. The last on record was Jan. 26, 1700.

That means another earthquake is neither impossible nor overdue, Nissen says.

“Prediction is probably impossible. Many of us think it will always be impossible, ” he says. “What we can do is forecast the location and magnitude – but instead of a [specific] time you give an interval of time and a probability.”

Nissen says research shows a 15 to 30 per cent chance of a major earthquake (magnitude 8 to 9) in the next 50 years, but that leaves an up to 70 per cent chance that there will be no earthquake at all – at least for the next five decades.

READ ALSO: Be Prepared: After the “Big One,” will your family be ready?

“Humans think over short time scales – we don’t think in decade or 100-year time spans,” Nissen says. “But for earthquake safety that’s the time span we need to think in.”

Nissen says infrastructure upgrades, emergency plans and advancing earthquake early warning technologies are all part of a necessary planning process – even if the next megathrust doesn’t hit until 2120.

Nissen quips, “If there was a 30 per cent chance of rain you would still bring an umbrella.”



nina.grossman@blackpress.ca

Follow us on Instagram
Like us on Facebook and follow us on Twitter.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

This illustration provided by the Centers for Disease Control and Prevention in January 2020 shows the 2019 Novel Coronavirus. This virus was identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China. [CDC]
Lake Cowichan daycare closes for 10 days due to COVID-19 exposure

A client at Creative Angels Daycare came in contact with someone who tested positive

(Pxhere)
Mill Bay nurse suspended after using Tensor bandage to trap long-term care patient in room

Susan Malloch voluntarily agreed to a three-day suspension of her certificate of registration

Cullen Ferguson has left the Cowichan Valley Capitals to play with the Aberdeen Wings of the NAHL. (Citizen file)
Cowichan Capitals say goodbye to Ferguson and Richter

The Caps traded another Union College commit away last week

Handwashing is one of the important COVID-19 precautions. (File photo)
Editorial: Time to knuckle down on COVID precautions

It would be foolish to think that we have not had any COVID cases in Cowichan until now

Maj.-Gen. Dany Fortin, vice-president of logistics and operations at the Public Health Agency of Canada, speaks at a news conference on the COVID-19 pandemic in Ottawa, on Friday, Jan. 15, 2021. THE CANADIAN PRESS/Justin Tang
B.C. records 500 new COVID-19 cases Wednesday, 14 deaths

Outbreak at Surrey Pretrial jail, two more in health care

Gov. Gen. Julie Payette takes the royal salute from the Guard of Honour as she makes her way deliver the the throne speech, Wednesday, September 23, 2020 in Ottawa. THE CANADIAN PRESS/Fred Chartrand
Gov. Gen. Julie Payette resigns after searing report into workplace culture: reports

Payette, who is the Queen’s representative in Canada, has been the governor general since 2017

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Grounded WestJet Boeing 737 Max aircraft are shown at the airline’s facilities in Calgary, Alta., Tuesday, May 7, 2019. WestJet will operate the first commercial Boeing 737 Max flight in Canada today since the aircraft was grounded in 2019 following two deadly crashes. THE CANADIAN PRESS/Jeff McIntosh
Passengers unfazed as WestJet returns Boeing 737 Max to service on Vancouver flight

After a lengthy review process, Transport Canada cleared the plane to return to Canadian airspace

The top part of the fossil burrow, seen from the side, with feathery lines from the disturbance of the soil – thought to be caused by the worm pulling prey into the burrow. (Paleoenvironntal Sediment Laboratory/National Taiwan University)
PHOTOS: SFU researchers find evidence of ‘giant’ predatory worms on ocean floor

Fossils found the prove the existence of an ancient Taiwanese worm as long as two metres

RCMP officers provide policing for 63 B.C. municipalities under a provincial formula based on population. (Black Press file photo)
B.C. communities warned of upcoming RCMP unionization costs

Starting salaries for city police officers are 30% higher

Abbotsford’s Skully White (left), who donated his kidney in December, has started a campaign to find other recipients and donors. The first candidate is retired police officer Gavin Quon. White owns and operates a hotdog stand, Lullys Food Experience, out of the Abbotsford Canadian Tire parking lot. (Facebook photo)
After donating his kidney, Abbotsford hotdog king starts donor campaign

Skully White donated his kidney to customer Tim Hiscock in December

Toronto-based director Michelle Latimer was recently scrutinized after years of claiming she was of Algonquin and Metis descent. (CANADIAN PRESS/Chris Young)
Haida activist calls for hefty fines, jail time against those who claim to be Indigenous

Filmmaker Tamara Bell proposing the Indigenous Identity Act – to dissuade ‘Indigenous identity theft’

Most Read