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.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

The Nov. 20 WestJet flight 3171 has been identified by the BC Centre for Disease Control with a COVID case aboard. (Black Press file photo)
Fifth COVID-19 exposure reported on flight at Comox airport

Another exposure risk from flight originating in Calgary

The School District 70 administration office in Port Alberni. AV NEWS FILE PHOTO
Four Alberni schools reporting COVID-19 exposures

Exposures occurred between Nov. 19 and Nov. 25 depending on the school

The Royal Canadian Legion Branch 160 Comox, B.C. Poppy Chairman, Kent Guilford presenting cheques to the following organizations in support of their venues: (top left) The Sea Cadet Corps who assisted in last year’s Poppy campaign. (Top right) CFB Comox, Military Family Resource Center, Kim Hetherington, executive director MFRC. Bottom, The Views at St Joseph’s, Jessica Aldred, Health Care Foundation, Michael Aikins, senior operations leader. We wish to Thank All those who supported last year’s Poppy Campaign and we hope we will have your continued support this year. Thank you all.
Comox Valley gives back

Spotlight on some of the groups, businesses and individuals who make the Comox Valley great

Union Bay voters chose a new direction Saturday. Photo by Mike Chouinard
Union Bay voters opt for governance change

More than seventy per cent support dissolving UBID to roll services into regional district

A bus shelter in White Rock is emblazoned with an ad from B.C.’s Office of the Human Rights Commissioner on Sunday, Nov. 29, 2020. (Black Press Media files)
VIDEO: ‘Am I racist?’ campaign asks British Columbians to confront their unconscious biases

Signs asking British Columbians to think about racial injustice have been put up across the province

Black Press Media and BraveFace have come together to support children facing life-threatening conditions. Net proceeds from these washable, reusable, three-layer masks go to Make-A-Wish Foundation BC & Yukon.
Put on a BraveFace: Help make children’s wishes come true

Black Press Media, BraveFace host mask fundraiser for Make-A-Wish Foundation

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

Jim Neufeld, 55, was last seen leaving his home in Penticton Jan. 21, 2009. (RCMP photo)
Human remains found off U.S. coast in 2009 identified as Penticton man

Jim Neufeld, 55, was last seen leaving his home in Penticton Jan. 21, 2009

Remains of the scene off Melrose Road in Whiskey Creek where three bodies were found on Nov. 1, 2020. (Mandy Moraes photo)
Probe continues into grisly mid-Island discovery of 3 human bodies, 4 dead dogs

Police still want to speak with motorist who picked up hitchhikers near scene on Nov. 1

An man from Errington died when his ATV went over an embankment on Northwest Bay Logging Road on the weekend. (File photo)
ATV rider goes over embankment and dies on back road near Nanaimo

45-year-old man from Errington died in incident Saturday afternoon

Mary Ellen Turpel-Lafond speaks to a reporter in Vancouver on November 13, 2015. (THE CANADIAN PRESS/Darryl Dyck)
No evidence that B.C. ER staff played blood alcohol level game, but Indigenous racism widespread

Mary Ellen Turpel-Lafond releases findings of independent investigation

Christmas lights are something that people can do to celebrate the season that are not impacted by COVID-19. (file photo)
Editorial: Holidays will be different this year

This Christmas is going to be very different for our communities on… Continue reading

(Dave Landine/Facebook)
VIDEO: Dashcam captures head-on crash between snowplow and truck on northern B.C. highway

Driver posted to social media that he walked away largely unscathed

Most Read