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

Tough year ahead for the aluminium industry

U.S. market is still Canada’s most important

Kitselas receive $1.2M boost for apprenticeship development program, open to Tsimshian and Haisla Nations

Melanie Mark, Minister of Advanced Education announces $7.5M for six Indigenous training programs

PHOTOS: Heavy snowfall breaks window, causing avalanche into Northern Sentinel office

It was a chaotic start to the week for the Kitimat Northern Sentinel

B.C. premier talks forestry, service needs with handful of northern mayors in Prince George

Prince George meeting completes premier’s tour of Kitimat, Terrace, Fort St. James and Quesnel

Indigenous LNG supporters chide human rights advocates over pipeline comments

Coastal GasLink has signed agreements with 20 elected First Nation councils along the pipeline’s 670-kilometre path

VIDEO: Mass coronavirus quarantines seen in China won’t happen in Canada, authorities say

‘If a case comes here, and it is probably … it will still be business as normal’

Province’s oldest practising lawyer shares advice at her 100th birthday party

Firefighters bring Constance Isherwood a cake with 100 birthday candles

Vernon woman suing McDonald’s for spilled coffee

Woman seeking nearly $10K, says employee failed to put lid on properly

Diners’ health tax not catching on in B.C., restaurant group says

Small businesses look for options to cover employer health tax

B.C. comic wins judgment after club owner slaps cellphone out of his hands

Incident happened last summer when Garrett Clark was performing in Abbotsford

Mayors call for ‘calmness’ as highway rockslide cuts Tofino, Ucluelet off from supplies

Ministry of transportation expects to open road for “essential travel only” from noon-8 p.m. Friday.

Owner surrenders dog suffering from days-old gunshot wound to B.C. SPCA

The dog was also found to be emaciated and suffering from a flea infestation

B.C. man dies after police called for ‘firearms injury’ in rural Alberta

Victim is 30-year-old Greater Victoria man, say police

Most Read