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/h, 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 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 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)

Earthquake seismologist Taimi Mulder of the Geological Survey of Canada explains plate tectonics. (Nick Murray/News Staff)

Earthquake seismologist Taimi Mulder of the Geological Survey of Canada explains plate tectonics. (Nick Murray/News Staff)

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

Just Posted

Head chef Travis Ashley dumps the first load of lobsters into the vats of boiling saltwater. (Jim Taylor - Contributed)
150 lobsters served in Lake Country drive-thru fundraiser

Rotary Club sees success in unique COVID-friendly lobster dinner event

Morning Star columnist Sam McNair puts the business spotlight on Expressions of Time in his latest article. (Sam McNair - Contributed)
Small Business Spotlight: Vernon bookstore specializes in more than literature

Expressions of Time is a beloved asset to the local business community

Fire truck.
Scooter struck in downtown Vernon

Traffic may be affected around 30th Avenue

Vernon-Monashee NDP MLA Harwinder Sandhu. (Contributed)
Vernon MLA marks International Women’s Day with first in-person legislature appearance

Harwinder Sandhu to speak in local panel hosted by CFUW later tonight

Five Kelowna writers are featured in an anthology that launched in time for International Women's Day. (Twila Amato - Black Press Media)
International Women’s Day: Book exploring fears features Kelowna writers

The book has launched in time for International Women’s Day

(Black Press Media files)
Hosts charged, attendees facing COVID fines after Vancouver police bust party at condo

Police had previously received 10 complains about that condo

It's tick season in South Okanagan.
Tick season has started in South Okanagan

A Penticton adventure company collected 200 ticks last year to be studied for Lyme Disease

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

Minister of Families, Children and Social Development Ahmed Hussen takes part in an update on the COVID pandemic during a press conference in Ottawa on Tuesday, Oct. 27, 2020. A joint federal and B.C. government housing program announced today aims to help people living in up to 25,000 vulnerable households pay their rent. THE CANADIAN PRESS/Sean Kilpatrick
Federal, B.C. governments announce $517-million rent aid program to help vulnerable

Benefits for those not eligible for B.C.’s Rental Assistance Program or Shelter Aid for Elderly Renters

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

(BC SPCA)
Is it safe to give your dog some peanut butter? Not always, BC SPCA warns

Some commercial peanut butter ingredients can be harmful to dogs

Phase four of the Kicking Horse Canyon project would twin the winding stretch of the Trans-Canada Highway just east of Golden. ~ Photo by B.C. Ministry of Transportation
Additional closures announced to Trans-Canada east of Golden

Additional closures will be needed in May as a part of Phase 4 of the Kicking Horse Canyon Project

Dawn Low first moved “upstairs” to the administrative department of the City of Revelstoke in 2009. (Jocelyn Doll - Revelstoke Review)
120 years later, first female CAO appointed in Revelstoke

International Women’s Day was first celebrated on March 19, 1911, in Austria,… Continue reading

Most Read