Open this photo in gallery Depending on how big an earthquake eventually hits in Vancouver, and where, means the lack of readiness could be costly. JONATHAN HAYWARD/The Canadian Press

Cars and people lie crushed under the slabs of a collapsed bridge. Nearby, boulders from a landslide have trapped vehicles and passengers. Emergency personnel pull bodies from the wreckage.

That was the scene last Friday in Vancouver – staged as a test of the city’s preparedness for a real earthquake. Hundreds of staff worked on exercises ranging from community-centre evacuations to the deployment of Vancouver’s urban search-and-rescue team. Mayor Kennedy Stewart said that “people should feel confident” about the city’s readiness.

They should – to an extent. But Vancouver and the entire West Coast are not as ready as they could be. Depending on how big an earthquake eventually hits, and where, that lack of readiness could be costly.

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If, for example, a magnitude 7.3 quake hits close to Vancouver, the provincial emergency-response plan forecasts as many as 10,000 dead and more than 100,000 injured. In the City of Vancouver alone, 150 buildings would likely collapse and 4,000 would be so severely damaged they would need to be demolished. Central neighbourhoods, home to older buildings, could be cordoned off for months. Canada’s entire economy would feel the blow, including from the interruption of the half-billion-dollars of cargo that flows through Vancouver’s port each day.

That big an earthquake, hitting the most populated part of the province, is the “worst-case” scenario, according to B.C.’s emergency-response plan. But reports have estimated the odds of a smaller but still significant quake in the region over the next half-century at one-in-four to one-in-three.

Two earthquakes recorded off Vancouver Island, no tsunami risk or damage reported

The odds of a really big one – a magnitude 9 event similar to the megathrust earthquake and tsunami near Japan in 2011 – was estimated by a B.C. auditor-general’s report at one-in-10 over the next half-century. That could occur along the Cascadia subduction zone, where two tectonic plates collide. It runs offshore from Vancouver Island to northern California. The last big quake in this area was in 1700.

A major challenge for earthquake planning in B.C. is that, while earthquakes are not unusual in the province or in coastal waters, major quakes on land and near population centres are rare. Few British Columbians remember the last big one, a magnitude 7.3 on Vancouver Island in 1946. The urgency is not obvious. However, the 2011 earthquakes in Japan and near Christchurch, New Zealand, sparked governments here to renew their efforts.

One example of the progress that has been made is an offshore early-warning system developed by University of Victoria’s Ocean Networks Canada. Covering the northern third of the Cascadia subduction zone, it is a first in North America.

Once in operation, the system will provide a crucial minute or two of warning to gird for disaster – similar to systems in Japan. That could give time for everything from diverting aircraft and slowing trains to opening bay doors at fire stations and alerting citizens. It’s a necessary earthquake-protection measure, but it isn’t yet up and running, and the B.C. government doesn’t have a plan for when it will be.

It’s not the only area where Canada has moved forward, but still lags. Seattle has pushed ahead on rules to retrofit older buildings susceptible to collapse, following the lead of cities in California. Vancouver has no plans to do the same.

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Among citizens, readiness varies. Two-thirds of homeowners in southwest B.C. have earthquake insurance, as do most businesses. A 2014 Statistics Canada survey showed that 54 per cent of households in the Vancouver area have emergency supply kits. In the Victoria area, it was 63 per cent.

Progress has been made – but more is still needed. B.C. spent $17-billion from 2000 through 2015 on seismic upgrades for public infrastructure. But in the province’s schools, the plan to retrofit high-risk buildings is slated to continue until 2030, with 176 schools on the waiting list.

Building codes have long ensured that new structures will not collapse during an earthquake, but some new buildings may suffer enough damage to be unusable, as happened in Christchurch.

The costs of a 9.0 Cascadia subduction zone megathrust earthquake could reach $75-billion, according to a study for the Insurance Bureau of Canada. The staggering number is more than B.C.’s annual provincial budget.

On Canada’s West Coast, earthquake readiness still isn’t where it needs to be. Being ready comes at a price, but not being ready comes at a far greater one.