A map showing earthquakes and the various tectonic plates around the Pacific Ocean. (Nick Murray/News Staff)

A map showing earthquakes and the various tectonic plates around the Pacific Ocean. (Nick Murray/News Staff)

Vancouver Island overdue for the big one, can also expect mega-thrust tsunami

The last big earthquake was 70 years ago in Courtenay

According to seismologists, Vancouver Island is overdue for a magnitude 7 earthquake and has entered a period of time where an additional magnitude 9 mega-thrust rupture earthquake, likely to cause a tsunami, can be expected.

“In our part of the world, there are the big Pacific and North American [tectonic] plates, and caught in-between the two is the Juan de Fuca plate system,” says Taimi Mulder, seismologist at the Geological Survey of Canada (GSC), which monitors all seismic activity in Western Canada.

ALSO READ: Scientists warn warmer and more acidic oceans threaten marine life

Over millions of years, these plates push and grind under and past each other in areas called subduction zones. Earthquakes are caused and can be tiny or they can be massive, like the 2004 Sumatran earthquake, which ruptured 1,000 kilometres of coastline.

“An earthquake is like ringing a bell. The earthquake is the clapper that sets it off and the bell reverberates,” said Mulder. “In an earthquake, energy is sent shooting in all directions and it pings around inside the earth making the whole earth vibrate.”

Magnitude 4 or 5 earthquakes will likely wake you up, while a 7 will result in toppled bookcases and fallen chimneys. Thanks to B.C.’s stringent building code, structural collapse is not expected in magnitude 7s. Magnitude 8 or 9s have the same severity of shaking as a 7, but their duration lasts longer, often over 2 or 3 minutes. They cause structural building damage and ruptured gas lines, often causing fire.

The last big Vancouver Island earthquake struck Courtenay in 1946 and measured 7.3 on the Richter scale. The GSC says quakes of this magnitude should happen every decade, so the Island is about 70 years overdue.

ALSO READ: Hundreds of floating ‘Sponge Bobs’ help track ocean currents

As well as this imminent quake, Mulder says we have entered the timeframe to expect a magnitude 9 mega-thrust rupture earthquake too. These Cascadia Subduction Zone earthquakes happen every 200 to 800 years, and the last one occurred 300 years ago. If it hits magnitude 9, it will cause a tsunami, wreaking havoc on some coastal communities on the Island.

While storms often whip up 100 or 200 metres worth of surface water, tsunamis move the whole water column, several kilometres of water, at over 700 km per hour, close to the speed of a jetplane.

The GSC collaborates with the nearby Institute of Ocean Sciences (IOS), whose world-class programmers and super computers model tsunami effects.

“We have the ability to simulate different earthquake scenarios,” says IOS acting manager of ocean sciences division Jon Chamberlain. “What type of wave it would likely generate, the likely maximum size of wave and how long it would take to reach certain parts of the coastline.”

ALSO READ: BC Ferries’ marine super talks dodging whales

Mulder explains one such scenario, “The wave that will hit the west coast is likely to be about 10m high, wrapping around the Island and being 4 or 5m by the time it hits Victoria, 1 or 2m when it reaches Vancouver.”

West coast residents will most likely receive hours of notice for tsunamis originating from across the Pacific, but only 15–45 minutes for those from the Cascadia Subduction Zone. There will be more time for people in Greater Victoria. Mulder advises that if a quake lasts longer than three minutes, it is likely magnitude 9 and a tsunami is incoming.



nick.murray@peninsulanewsreview.com

Like us on Facebook and follow us on Twitter

EarthquakeTsunami

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

 

A map showing every western B.C. earthquake of the last 20 years in a glass display case. (Nick Murray/News Staff)

A map showing every western B.C. earthquake of the last 20 years in a glass display case. (Nick Murray/News Staff)

A computer system that records seismological data in real-time, from instruments around the coast and in the sea. (Nick Murray/News Staff)

A computer system that records seismological data in real-time, from instruments around the coast and in the sea. (Nick Murray/News Staff)

A display graphic showing the Cascadia Subduction Zone. (Nick Murray/News Staff)

A display graphic showing the Cascadia Subduction Zone. (Nick Murray/News Staff)

Vancouver Island overdue for the big one, can also expect mega-thrust tsunami

Just Posted

Food trucks will be allowed to operate in several Sooke parks beginning May 1. (Black Press Media file photo)
Sooke’s food truck pilot project under scrutiny

Councillor questions impact food trucks will have on nearby restaurants

A walk for autism awareness. (Black Press Media file photo)
COLUMN: Autism acceptance, not autism awareness

Elizabeth Sparling is the mother of a 24-year-old son with Autism Spectrum Disorder

A vehicle that was driven through the wall of a parkade at Uptown Shopping Centre and into the nearby Walmart on April 9 was removed through another hole in the wall later that night. (Photo via Saanich Police Department and Ayush Kakkar)
PHOTOS: Vehicle driven into Saanich Walmart removed after two trapped workers rescued

Crews cut new hole in parkade wall to remove vehicle safely

Tons of bottles were donated during bottle drives in Sooke and Langford on March 27. The funds raised from the drives will help a local family stay with their daughter during her leukemia treatments in Vancouver. (Photos: Glendora Scarfone)
Sooke, Langford bottle drives help cover family’s costs of staying with daughter during cancer treatments

More than $11,900 raised to help Shae Hanilton’s family stay with her in Vancouver

B.C. Health Minister Adrian Dix and Premier John Horgan describe vaccine rollout at the legislature, March 29, 2021. (B.C. government)
1,262 more COVID-19 infections in B.C. Friday, 9,574 active cases

Province’s mass vaccination reaches one million people

Organ donation form from BC Transplant. (BC Transplant)
POLL: Have you registered as an organ donor?

They number 1.5 million strong and growing. But their numbers still fall… Continue reading

Anyone with information on any of these individuals is asked to call 1-800-222-TIPS (8477) or visit the website victoriacrimestoppers.ca for more information.
Greater Victoria Crime Stoppers wanted list for the week of April 6

Greater Victoria Crime Stoppers is seeking the public’s help in locating the… Continue reading

Two-year-old Ivy McLeod, seen here on April 9, 2021 with four-year-old sister Elena and mom Vanessa, was born with limb differences. The family, including husband/dad Sean McLeod, is looking for a family puppy that also has a limb difference. (Jenna Hauck/ Chilliwack Progress)
B.C. family looking for puppy with limb difference, just like 2-year-old Ivy

Ivy McLeod born as bilateral amputee, now her family wants to find ‘companion’ puppy for her

Four members with Divers for Cleaner Lakes and Oceans were out at Cultus Lake on March 28 and 29 hauling trash out of the waters. (Henry Wang)
PHOTOS: Out-of-town divers remove 100s of pounds of trash from Cultus Lake

Members of Divers for Cleaner Lakes and Oceans hauled out 470 pounds of trash over two days

As of Saturday, April 10, people born in 1961 are the latest to be eligible for a COVID-19 vaccine. (Black Press files)
B.C. residents age 60+ can now register to get their COVID-19 vaccine

Vaccine registration is now open to people born in 1961 or earlier

A new saline gargle test, made in B.C., will soon be replacing COVID-19 nasal swab tests for kids. (PHSA screenshot)
Take-home COVID-19 tests available for some B.C. students who fall ill at school

BC Children’s Hospital plans to provide 1,200 kits to Vancouver district schools this April

Ruming Jiang and his dog Chiu Chiu are doing fine following a brush with hypothermia that saw several people work together to get them out of the Fraser River near Langley’s Derby Reach Park on March 25, 2021 (Special to the Advance Times)
Man finds men who rescued him from drowning in B.C.’s Fraser River

A grateful Ruming Jiang says he will thank them again, this time in person when the pandemic ends

Tyson Ginter, 7, is proud of his latest Hot Wheels he recently received by Quesnel RCMP Const. Matt Joyce. (Photo submitted)
B.C. Mountie handing out toy cars to light up children’s faces

‘A lot of times it will be the only interaction they have with the police,’ says Const. Matt Joyce

Most Read