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

Meet the 2020 Words on the Water authors

Eight authors for spring literary festival all have different backgrounds

Words on the Water returns for 19th year

March event expected to sell out, says organizer

Campbell River City Council postpones decision on Campbellton ‘entertainment venue’

Current liquor license doesn’t mesh with business plan, council says, wants ‘assurances’ for neighbours

Alcohol believed to be a factor in fiery crash in Campbell River

No one seriously injured, charges are being sought for impaired driving.

SD72 facing a shortfall of more than $1-million

Board will likely be asked to approve a draw on surplus to have balanced budget

VIDEO: Feds look to help 126 Canadians quarantined in China for coronavirus

China has confirmed more than 4,500 cases of the new virus, with more than 100 deaths

Off-duty Nanaimo Mountie takes down would-be ice cream thief

Suspect attempted to steal Dilly Bars from Dairy Queen location on Sunday

Sap thief taps Saanich park maple trees, faces hefty fine

One tree found with four taps in Mount Doug Park

Nanaimo man hit with pole in dispute over off-leash dog

RCMP say no charges recommended at this time

Was there a tornado on Vancouver Island Monday?

Suspected phone app glitch gives eerie warning

Work has started on Malahat Skywalk, expected completion in 2021

$15-million project expected to open in spring, 2021

B.C. reports first coronavirus in Vancouver region

First patient visited Wuhan, China, reported symptoms

Uber threatens legal action to ‘defend its right’ to operate in Surrey

‘I have no concerns,’ Mayor Doug McCallum replies

Victoria resident says WestJet employee uttered racist comment, refused to let her on plane

Customer claims she was told ‘You guys can’t handle your alcohol’ by WestJet employee

Most Read