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.

Just Posted

A CH-149 Cormorant from 442 Transport and Rescue Squadron out of CFB Comox on a training exercise in Chilliwack on June 16, 2021. (William Snow photo)
VIDEO: Military search and rescue training in Chilliwack Wednesday

CH-149 Cormorant and CC-115 Buffalo from CFB Comox participated in downed aircraft rescue simulation

Stock photo by LEEROY Agency from Pixabay
Drop-in vaccination clinics slated in Abbotsford for construction workers

Among three sites in Lower Mainland holding no-appointment clinics in June and July

In this pre-pandemic meeting at the Friendship House in Agassiz, a packed house of residents expressed their concerns for and against the Teacup properties exclusion application to the ALC. The ALC recently denied the exclusion, keeping the McDonald Road properties as agricultural land. (File Photo/Adam Louis)
ALC refuses Teacup properties exclusion application

The decision comes nearly one year after application submitted

Chilliwack Spartans Swim Club coach Justin Daly.
Chilliwack Spartans swim coach Justin Daly wins Rubber Boot Award

Daly was recognized in a vote by fellow coaches in the BC Swim Coaches Association

Linnea Labbee outside the Chilliwack Law Courts on April 1, 2021 on day 16 of her trial in BC Supreme Court. Labbee was convicted April 12 for the fatal hit-and-run of 78-year-old Fourghozaman Firoozian on Dec. 1, 2016. (Paul Henderson/ Chilliwack Progress)
Sentencing hearing scheduled for 72-year-old Chilliwack woman found guilty in fatal hit-and-run

Crown will seek jail time for Linnea Labbee who struck and killed 78-year-old woman in 2016

People line up to get their COVID-19 vaccine at a vaccination centre, Thursday, June 10, 2021 in Montreal. THE CANADIAN PRESS/Ryan Remiorz
Vaccines, low COVID case counts increase Father’s Day hope, but risk is still there

Expert says people will have to do their own risk calculus before popping in on Papa

The first suspension bridge is the tallest in Canada, with a second suspension bridge just below it. The two are connected by a trail that’s just over 1 km. (Claire Palmer photo)
PHOTOS: The highest suspension bridges in Canada just opened in B.C.

The Skybridge in Golden allows visitors to take in views standing at 130 and 80 metres

B.C. Premier John Horgan leaves his office for a news conference in the legislature rose garden, June 3, 2020. (B.C. government photo)
B.C. premier roasted for office budget, taxing COVID-19 benefits

Youth addiction law that triggered election hasn’t appeared

A vial containing the Moderna COVID-19 vaccine is shown at a vaccination site in Marcq en Baroeul, outside Lille, northern France, Saturday, March 20, 2021. THE CANADIAN PRESS/AP/Michel Spingler
mRNA vaccines ‘preferred’ for all Canadians, including as 2nd dose after AstraZeneca: NACI

New recommendations prioritizes Pfizer, Moderna in almost all cases

Join Black Press Media and Do Some Good
Join Black Press Media and Do Some Good

Pay it Forward program supports local businesses in their community giving

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Homicide investigators say the disappearance of a 33-year-old Burnaby man is linked to ongoing gang warfare in the Lower Mainland. (IHIT)
Disappearance of Burnaby man no accident, foul play suspected: IHIT

Parminder Paul Rai, 33, is known to police for his connection to drug and gang activity, says Sgt. Frank Jang

Surrey Mayor Doug McCallum speaks at a press conference in August 2019 about provincial government approval of the city’s change to a municipal force, joined by councillors (from left) Mandeep Nagra, Allison Patton and Doug Elford. Members of the National Police Federation claim there is still no transition plan in place although Surrey RCMP’s contract with the city is due to end March 31.(File photo)
Elections BC approves petition application for referendum on Surrey policing transition

Application was filed under Recall and Initiative Act by the widow of a Surrey murder victim

Fiery crash on the Okanagan Connector between two semis. (Facebook)
One dead after fiery Okanagan Connector crash between two semis

DriveBC estimates road won’t be open until 5 p.m.

Most Read