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

Rio Tinto Alcan’s aluminum smelter at Kitimat competes against producers in the Middle East and Russia that have no carbon tax. (Rio Tinto)
B.C. carbon tax highest in Canada, export industries unprotected

B.C. NDP, B.C. Liberals say they’re looking at exemptions

Keep a lookout for monsters around Kitimat during the week leading up to Halloween. (Black Press file photo)
Lions and tigers and…monsters? Oh my!

Find monsters hiding around town during the week leading up to Halloween to be entered for a prize

Liz Thorne is president of the Snow Valley Ski Club, and has been involved with the club and cross country skiing for over 30 years. (Clare Rayment)
In Our Valley: Liz Thorne

Thorne has been involved with the Snow Valley Ski Club for over 30 years

The car was trapped, with its driver inside, in a ditch off Hirsch Creek Main near Onion Lake overnight Monday (Oct. 19). Oct. 20, 2020. Kitimat RCMP photo.
Man found after spending overnight stuck in car in a ditch near Onion Lake

Kitimat RCMP said the man was stuck there overnight for about 10 hours

Provincial health officer Dr. Bonnie Henry presents modelling of COVID-19 spread in B.C., March 25, 2020. (B.C. government photo)
B.C. sets another COVID-19 record with 203 new cases

up to 1,766 active cases in B.C., two more deaths

RCMP. (Phil McLachlan - Black Press Media)
British Columbia man dies during ski trip near glacier west of Calgary

Kananaskis Public Safety and Alpine Helicopters responded around 2:30 p.m.

Prime Minister Justin Trudeau arrives on Parliament Hill in Ottawa on Monday, Oct. 19, 2020, following a week-long break for the House of Commons. THE CANADIAN PRESS/Sean Kilpatrick
One crisis after another for Trudeau since last federal election one year ago

It has been a year of unprecedented calamity and crisis

Join Black Press Media and Do Some Good

Pay it Forward program supports local businesses in their community giving

Rio Tinto Alcan’s aluminum smelter at Kitimat competes against producers in the Middle East and Russia that have no carbon tax. (Rio Tinto)
B.C. carbon tax highest in Canada, export industries unprotected

B.C. NDP, B.C. Liberals say they’re looking at exemptions

(Pixabay)
Vancouver teacher suspended after swearing, touching students and complimenting underwear

McCabe touched students, including rubbing their backs and necks, touching their hair and hugging them

A glimpse of some of the 480 (approx) cars written off as a result of the acid spills along the Trail highway in 2018. Photo: Trail Times
2 years after huge highway acid spill, Kootenay Ford dealer’s frustration grows with ICBC

Trail AM Ford owner Dan Ashman says he just wants fair compensation from ICBC

Mail-in ballot from Elections BC (Katya Slepian/Black Press Media)
At least 26% of eligible voters have already cast their ballot, Elections BC says

Voters can cast a ballot until 8 p.m PST on Election Day

Most Read