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

 

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

Just Posted

Sooke’s First Nations have Iroquois links

References to the proud Iroquois race tend to make one think of… Continue reading

Mad Hatter’s Ball offers laughs in support of Boys and Girls Club

Annual fundraising event features improv performances at McPherson Playhouse May 24

Carbon dioxide at highest levels for over 2.5 million years, expert warns of 100 years of disruption

CO2 levels rising rapidly, now higher than at any point in humanity’s history

SidFest 7 ready to rock the Mary Winspear Centre

The Bankes Brothers and Madrona Drive headlining May 24 concert

Penelakut filmmaker Steve Sxwithul’txw finds success in film and TV

Cop-turned-storyteller reaches back to his past for Tribal Police Files

Kelowna RCMP interrogation video brings home reality in ‘visceral way’: former TRC chairman

Video of Mountie interrogating young Indigenous woman disclosing sexual abuse under fire

Canadian killed in Honduras plane crash

The crash happened in the Roatan Islands area, according to officials

B.C. ferry stops to let black bear swim past near Nanaimo

Queen of Oak Bay brakes for wildlife in Nanaimo’s Departure Bay

Mother dead, child in critical condition after carbon monoxide poisoning at Shuswap campground

The woman was found unresponsive insider her tent and the youth was taken via air ambulance to hospital

Canada’s parole officers say correctional system has reached breaking point

About half of Canada’s federal parole officers work inside penitentiaries and correctional institutions

Montreal researchers create audible hockey puck for visually impaired players

Three years ago, Gilles Ouellet came up with the idea for a puck that makes a continuous sound

Vancouver Island MusicFest: ‘House bands’ from the golden age of rock and R&B

Some of America’s greatest session musicians are coming to the Comox Valley this summer

Former B.C. Greyhound bus drivers head to Penticton for goodbye party

Big bash runs until Sunday, funded by drink cans left behind on busses over the years

Boy, 12, arrested after allegedly pulling a knife on another child at a Surrey park

The child was later released into his parents’ custody as Surrey RCMP continue their investigation

Most Read