Experts: Vancouver Island will NOT ‘rip open like a zipper’

 

 

Kate Moran wants to set the record straight.

“There’s no way Vancouver Island will rip open like a zipper,” said the ocean engineer who heads up the Oceans Network Canada at the University of Victoria.

Moran, whose program monitors the ocean around the clock via data-collecting cables linked with the internet, was stung by Canada-wide headlines this week that turned her comments about Boxing Day 2004’s major Indian Ocean earthquake into a dire warning that Vancouver Island would somehow “rip open like a zipper” in case of a megathruster subduction earthquake. 

“I was describing the way that the Indian Ocean earthquake had occurred in a fault system there,” Moran said. The offshore system had a domino effect, the way the tines of a zipper interlock one at a time, she said. 

That actual epicenter will be in a certain location, but the system is hundreds of kilometres long, she said. 

“It just got misinterpreted,” she said. 

Alison Bird, a Natural Resources Canada seismologist also interviewed for the “zipper” article, said if she believed an earthquake would rip the Island like a zipper, “I wouldn’t be living here (in Victoria),” she said.

The 315th anniversary of the January 26, 1700 earthquake that destroyed a number of First Nations communities on the West Coast is approaching. 

And yes, even for something that occurred 315 years ago, they know the date and time. 

“The tsunami it generated impacted the east coast of Japan,” she said. Using Japanese history and reverse modeling corroborated by First Nations oral tradition, experts have placed the Last Megathrust Quake at 9 p.m., Jan. 26, 1700 

“It completely jives with First Nations oral history of a big earthquake and then a tsunami hitting the coastline,” she said. 

Before the 1700 temblor, megathrust quakes struck every 200 to 800 years. 

“The anniversary is a good time to remind people we’re living in a seismically active region. Be prepared and be aware,” she said. 

“It’s good for people to be aware, participate in the Great Canadian Shakeout drill in October,” Bird said. 

Within the next half-century, there is a 1-in-10 chance of a megathrust earthquake – a big subduction zone earthquake that releases hundreds of years of pent-up stress between major earth plates, Bird said. 

There is a 1-in-3 chance of a “damaging” earthquake on Vancouver Islands within the next half-century. That’s a quake of 6.5 or above, close to a populated area, where there is structural damage. 

That means the strength  of a building could be compromised; a chimney could come down. 

During the 2012 Haida Gwaii quake that registered 7.8, buildings had cracks in plaster, three chimneys were damaged. That one was epicentred 65 km from highly populated areas. There was strong shaking, and a power outage in the region. 

In a major quake, shaking goes on for several minutes. For residents who live near sea level, that means when the shaking stops, there is that many minutes fewer than the projected 20 minutes to get 20 metres (or even higher, if you comfortably can), Bird said. 

On the other hand, the quake much of Vancouver Island felt on Jan. 7, 2015 was centred 13 km from Tofino. It was rated 4.6, and although it was actually 40 km below the earth’s surface, it could be felt strongly because it was right under the West Coast on the subducting Juan de Fuca plate, she said. 

To prepare a house for earthquakes, things like making sure the house is bolted to the foundation can help. Tall shelves can be secured to studs to prevent toppling; earthquake damage is often about things falling. 

And above the bed? Maybe a soft, light tapestry instead of heavy framed pictures, Bird said. 

Bird visited the West Coast with last year’s successful Earthquake Tsunami Roadshow, and she found West Coasters to be very proactive.

“It was very encouraging,” she said. 

 

jcarmichael@westerlynews.ca