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

 

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)

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

Just Posted

Second Avenue location home for Coal Town Goods

Fernie’s own Coal Town Goods moved to a new location on Second… Continue reading

City of Fernie flips the switch on holiday cheer

Residents of Fernie gathered at the courthouse on Friday night to watch… Continue reading

Judgement Night III seeking locals to step in the ring and take a hit for charity

Are you ready to rumble? If not, it’s time to start training.… Continue reading

New general director for francophone association

Exciting things are on the horizon for the Association Francophone des Rocheuses… Continue reading

First responders host holiday food drive

Frozen fingers knocked on doors around Fernie on Wednesday evening as part… Continue reading

VIDEO: SNL skewers Trudeau’s mockery of Trump in high school cafeteria sketch

The three world leaders won’t let Trump sit at the cool kids’ table

Kovrig clings to humour as ‘two Michaels’ near one year in Chinese prison

Their detention is widely viewed as retaliation for Canada’s arrest of Chinese high-tech scion Meng Wanzhou

B.C. VIEWS: An engine that hums right along

First Nations are leading a new surge of investment in B.C.

Brain injury from domestic abuse a ‘public health crisis,’ says B.C. researcher

Nearly 80% of the domestic violence victims who reported to police last year were women

Campbell River mom’s iPhone containing priceless photos stolen from Victoria hospital parkade

The phone contained photos, heartbeat recordings of her late son

Miller nets winner as Canucks edge Sabres 6-5 in OT

Roussel, Leivo tally two apiece for Vancouver

‘Norovirus-like’ outbreak interrupts Bantam hockey showcase in Greater Victoria

Several athletes were sent home, quarantined on the ferry

$578: that’s how much your first distracted driving ticket will cost with recent premium hikes

Over 50 per cent of Canadians admitted to using phone while driving last year, according to study

Kelowna man attempts to steal bait bike from RCMP parking lot

38-year-old Brian Richard Harbison is facing several charges

Most Read