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

Surrey Fire Service is on scene of a fire in the 12300-block of 72A Avenue Saturday morning (April 10). (Photo: Shane MacKichan)
Surrey crews on scene of house fire

It happened in the 12300-block of 72A Avenue

Signage on a South Surrey sidewalk reminds pedestrians to respect social-distancing guidelines. (Photo: Tracy Holmes)
Surrey records 4,400 COVID-19 cases in March

New cases almost doubled between February, March

Surrey RCMP are looking for these two men after a bank in the 12800-block of 96th Avenue was robbed on March 12. (Images: Surrey RCMP)
Police release images of two men suspected of robbing Surrey bank

Robbery happened on March 12 at bank in 12800-block of 96th Avenue

An example of a Surrey Police cruiser, showcased at Mayor Doug McCallum’s State of the City Address at Civic Hotel in May of 2019. (File photo: Amy Reid)
Recently hired inspector no longer ‘taking a position’ with Surrey Police Service

Jeff Harris was first announced as an inspector on April 1

A vaccine-filled needle awaits injection, during a COVID-19 vaccination clinic held Jan. 15, 2021 at Amica White Rock. Community Living B.C.-funded workers learned April 8 that they, too, can now be vaccinated. (Tracy Holmes file photo)
Support workers for those with disabilities given vaccine priority

News shared with Community Living B.C.-funded staff on April 8

B.C. Health Minister Adrian Dix and Premier John Horgan describe vaccine rollout at the legislature, March 29, 2021. (B.C. government)
1,262 more COVID-19 infections in B.C. Friday, 9,574 active cases

Province’s mass vaccination reaches one million people

The 10-part Netflix series Maid, which is being exclusively shot in Greater Victoria, was filming near Prospect Lake in Saanich last month. (Photo courtesy Fred Haynes)
Province announces $150,000 towards South Island film studio, fulfilling B.C. NDP promise

Investment to fund movie studio feasibility study at Camosun College

Tyson Ginter, 7, is proud of his latest Hot Wheels he recently received by Quesnel RCMP Const. Matt Joyce. (Photo submitted)
B.C. Mountie handing out toy cars to light up children’s faces

‘A lot of times it will be the only interaction they have with the police,’ says Const. Matt Joyce

People stroll through rows of tulips in bloom during the Tulips of the Valley Festival on May 2, 2017. The colourful spring event, now called Chilliwack Tulips, opens on Sunday, April 11, 2021. (Jenna Hauck/ Chilliwack Progress file)
Fraser Valley tulip attraction returns this weekend for 1 month

More than 6.5 million bulbs in all at this year’s colourful Chilliwack Tulips event

Chief Public Health Officer Theresa Tam speaks during a technical briefing on the COVID pandemic in Canada, Friday, January 15, 2021 in Ottawa. THE CANADIAN PRESS/Adrian Wyld
Canada’s ICUs see near-record of COVID-19 patients last week as variant cases double

Last week, Canadian hospitals treated an average of 2,500 patients with COVID-19, daily, up 7% from the previous week

University of Victoria rowing coach Barney Williams at the University of Victoria in Victoria, B.C. THE CANADIAN PRESS/Chad Hipolito
UVic, women’s rowing coach deny former athlete’s allegation of verbal abuse

Lily Copeland alleges coach Barney Williams would stand close to her and speak aggressively in the sauna

Librarian Katie Burns with the Fraser Valley Regional Libraries poses for a photo in Chilliwack on June 18, 2019. Monday, April 12, 2021 is Library Workers’ Day. (Jenna Hauck/ Chilliwack Progress file)
Unofficial holidays: Here’s what people are celebrating for the week of April 11 to 17

Library Workers Day, That Sucks! Day, and Wear Your Pyjamas to Work Day are all coming up this week

Robinson Russ, 37, was fatally stabbed on April 4, according to a statement from police. THE CANADIAN PRESS/Darryl Dyck
Vancouver police name victim following city’s fourth homicide of 2021

Robinson Russ, 37, was fatally stabbed Sunday in the Downtown Eastside

Most Read