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

Maple Ridge Museum hosts time travelling photo contest

Residents are asked to replica 10 old images from the museum archives – and have fun while doing it

Pitt Meadows and Maple Ridge seniors honoured in novel ways for Seniors’ Week

Traditional gatherings are out, but local seniors groups wanted to mark the occasion

LETTER: Most take on healthcare to save lives, not get more money

Reader disturbed by call local person’s call for hazard pay during COVID

LETTER: Different view questions mandated social distancing

Look at the science behind herd immunity versus current approach to curtailing COVID

LETTER: Verbal attack on foreign workers disturbing

Racist and derogatory comments on social media disheartening and disappointing to Maple Ridge native

VIDEO: Injured bald eagle rescued in B.C. First Nations community

Bird suspected injured in fight, whisked off to Coquitlam rehab

Facing changes together: Your community, your journalists

Thanks for helping The News to continue its mission to provide trusted local news

Human Rights Tribunal denies church’s request to toss out White Rock Pride Society’s complaint

Star of the Sea and White Rock Pride Society to go to Human Rights Tribunal hearing

B.C.’s Central Kootenay region declares state of emergency, issues evacuation orders

The evacuation alert covers all areas except the Cities of Castelgar and Nelson

‘I’m afraid’: Witnesses of wolf attack on senior near Prince Rupert worried about safety

Frank Russ shows where the unprovoked wolf attacked his father

Protesters prepare to rally against racism in front of Vancouver Art Gallery

Rally is in response to the deaths of black Americans and a Toronto woman

Protesters rally against anti-black, Indigenous racism in Toronto

Police estimated the crowd to be between 3,500 and 4,000 and said there was no violence

Feds earmark $1.5M to support recovery of B.C., Indigenous tourism

B.C. money will be split between Vancouver Island and Indigenous tourism

‘We’re sick of it’: Anger over police killings shatters U.S.

Tens of thousands marched to protest the death of George Floyd

Most Read