Mayor admits many Vancouver buildings vulnerable
Published Friday, March 11, 2011 4:00PM PST Last Updated Saturday, May 19, 2012 1:09AM PDT
Older buildings in Vancouver would be vulnerable to an earthquake similar to the 8.9-magnitude quake that struck Japan, the city's mayor said Friday.
While Vancouver and the province of B.C. have invested millions of dollars in seismic upgrades for bridges, schools and public buildings, Mayor Gregor Robertson admits that nothing has been done to reinforce private buildings against the potentially disastrous effects of a major natural disaster.
"It is certainly a concern given the amount of buildings that are at risk," Robertson told CTV News Friday afternoon.
A prominent earthquake expert sounded the alarm about the vulnerability of private apartment and office towers in B.C. after the quake, saying authorities should start looking at "the many" apartment and office buildings that would likely sway and collapse.
"There's no process in place whatsoever to look at those occupied buildings. That's a major problem," Perry Adebar of the University of B.C. Earthquake Lab told ctvbc.ca in a telephone interview.
With its long history of major quakes, Adebar says Japan has made major improvements in its building code to ensure they will be seismically sound. But B.C. hasn't.
"We don't have the advantage of having a history of significant earthquakes that have taught us the lessons we need to know to keep us safe," he said.
Adebar says it's not the tallest buildings that are the most at risk here, but rather the ones that were constructed by a single engineer and weren't subject to a peer review.
Robertson says many buildings in Vancouver were built before new construction codes were introduced, and the city has "real questions" about what to do to update codes.
"With the private buildings built under old building codes there are real vulnerabilities there," he said.
Adebar believes the biggest problem is that no one is required to examine existing privately-owned buildings to make sure they are earthquake-ready.
The only time these buildings will have an inspection is if they are to be converted into condominiums or change occupancy.
"It's rare," Adebar said.
West Coast building standards
It's not just old buildings that are vulnerable, says Adebar. The way modern buildings are constructed in B.C.'s earthquake zones may also put us at a major risk.
Studying the effects of the 2009 Megaquake in Chile, Adebar found that many of the buildings that were most affected were newer apartment and office towers reinforced with thinner, six-inch concrete walls for support.
B.C. has nearly identical building codes. The thinner walls have become popular in both Chile and North America because they allow for additional parking in underground parkades -- where buildings need to be their strongest.
The results prompted him to call for urgent changes to the building code in British Columbia.
He says buildings built on flood plains and on sandy soils, similar to Richmond, south of Vancouver, had the biggest problems in Chile.
"Chile is a very modern country and we have six-inch walls just like this in Canada," he said.
Ken Elwood, an engineer with the UBC Earthquake Lab, spent three months in Japan in 2009 studying its building designs and says the country made great strides to minimize damage by retrofitting old buildings.
Elwood says the only way British Columbia will survive a major quake is to do the same thing.
"We need to learn as much as we can about the damage out there and bring it back here to improve our own structures," he said.
He says there's no way to completely stop a building from becoming damaged in an earthquake, but in cases like Japan, that's not the goal.
"The most important thing is life safety – that people can leave the buildings safely," he said.
Not just the "big one"
Experts say it isn't just "the big one" that would hurt Canada's West Coast.
Because the length of the subduction zone near British Columbia is much larger than other countries, say Chile's, a large quake has the capacity to shake the earth for a longer time.
That means a quake could have a smaller magnitude and cause a lot more damage.
"One that has a short span could be a lot more damaging – look at Christchurch," Adebar says, referencing the New Zealand 6.3-magnitude quake that killed 166 people last month.
Also important is how close the quake hits to the West Coast. A quake with a shorter duration that hits closer to Vancouver could be the most devastating, Adebar says.