B.C. homes need a big fix before the big one hits, says seismic engineer

A B.C. seismic engineer says thousands of buildings and lives are at risk in an earthquake if governments do not spend billions on making homes safer.

Schools need to be seismically upgraded — but it turns out many of our homes do, too

This graphic shows the Cascadia subduction zone — the Juan de Fuca plate moving toward and riding under the North America plate. The stress builds up over hundreds of years and it releases in a megathrust earthquake. (CBC)

As a parent raising three young children in an earthquake zone, I've spent the last nine years trying not to worry about a massive megathrust event shaking me, my family, and everything around us violently for several minutes.

Usually, I sleep pretty soundly in the 1912 wood-frame house my family calls home. I reassure myself with the belief the house will remain standing during the big one. Everyone inside will be okay, I think. We just need to drop, cover, and hold on.  

Well, that's what I thought. But then I spoke to Graham Taylor.

Seismic engineer Graham Taylor says thousands of buildings and lives are at risk.

Taylor is a structural engineer in Greater Victoria, who has worked extensively on the province's $2.5-billion school seismic program. 

He thinks making schools safer for tens of thousands of students is important. But he stresses the schools are only a small fraction of the vulnerable buildings in B.C., and many old houses also need fixing. 

Thousands of houses could collapse

"It's my personal opinion that we have several thousand houses that are going to collapse in the southern Greater Victoria area," Taylor told me. "We could have easily 2,000 fatalities."

This is what surprised me the most.

It may sound naive, but up until now I'd thought that people would be relatively safe in their houses, if those houses are made of wood. 

Timber-frame construction is generally safer in an earthquake than unreinforced brick and cinder block buildings, which are more prone to collapse when the shaking starts. 

But that doesn't mean all wood houses are safe. 

Taylor said the massive Cascadia megathrust earthquake that will one day shake large portions of southern B.C. and the U.S. Pacific Northwest will be especially hard on older houses.

Of particular concern are the basement walls, between the concrete foundation and the main floor. Many of those walls are not strong enough to support the weight of the house above once it starts shaking. And when those weak basement walls are in houses built on unstable ground, the results could be deadly.

"If we have a significant shake, they're going to collapse because of the form of construction, the bad soils, and the high seismicity. It's a nasty, nasty combination," he said.

Taylor believes as many as 30,000 buildings on southern Vancouver Island could be heavily damaged, and be off-limits to their owners for months or even years.

He said the number of homes would be similar in Metro Vancouver. If a major seismic event were to happen now, Taylor suggests that as many as 150,000 people would not be able to go back to their homes on B.C.'s South Coast.

Thousands of older houses will need seismic upgrades, according to engineer Graham Taylor. This Victoria house has already had one. (photo: Graham Taylor)

Earthquake will cost B.C. billions

The economic impact of a massive natural disaster in the future is difficult to predict, but a 2013 study from the Insurance Bureau of Canada pegs the costs of a 9.0-magnitude quake off the B.C. coast at $75-billion. Others predict it would top $100-billion.

The numbers are sobering, but Taylor and a small group that includes economists and Green Party leader Elizabeth May insist much of the pain can be avoided.

This fall they will meet with Canada's Public Safety Minister, Ralph Goodale, and other cabinet ministers to urge the federal government to set up a fund they would call BRIC - Building Resilience in Canada.

The idea behind BRIC is relatively simple, if expensive. Building owners in B.C. and in the seismically-active Ottawa-Montreal corridor would be eligible for matching government grants for any seismic improvements done to their property.

So if strengthening the concrete foundation and old basement walls of a 100-year-old house costs $30,000, the homeowner would pay half and the federal and provincial governments would cover the rest.

Seismic upgrades to old homes may include adding plywood to basement stud walls. (photo: Graham Taylor)

That may make a seismic fix an affordable option for many homeowners, but the BRIC proposal would also see governments paying more than $30-billion over the next three decades.

For Graham Taylor, it would be money well spent.

"If you want to talk money, this is something that you can't afford not to do. It's the only disaster in Canada of its magnitude that is effectively preventable."

Like many West Coast homeowners, I've already got a mountain of a mortgage to pay off, and I don't fancy the idea of owing more.

But I'm not sure I'll sleep so soundly tonight.

About the Author

Gregor Craigie


Gregor Craigie is the host of On The Island on CBC Radio One in Victoria. Past journalistic lives include reading the news at the BBC World Service, political reporting on TV, and freelancing in Asia.