Housing

After the shaking, somebody has to walk up to each building, judge it, and leave a placard on the door. In Greater Vancouver, the province’s magnitude 7.0 crustal scenario counts 10,000 buildings red-tagged as uninhabitable and 6,100 yellow-tagged as conditionally inhabitable. [1]

The yellow tag is the condition most people would be in: the building stands, entry is restricted, and nobody has said for how long.

Behind every placard is a queue. In a Cascadia earthquake, damage assessment teams are expected to be overwhelmed, leaving “about two million people in need of alternate housing”. [3] That count is province-wide, and it comes from the province’s written scenario, not a model run. [3]

In Vancouver, areas with high concentrations of damage may be closed off “for weeks, months, or even years”, and the West End and the Downtown Eastside are the neighbourhoods most at risk of it. [2]

The City draws a cordon around an area and ties it to concentrations of damage, not to any single address. [2] That is why displacement counts run so far above red-tag counts. A building that came through the shaking can sit inside a closed block, and nobody lives in it while the block is closed.

The scarce resource is people. Every building needs somebody qualified to assess it and somebody qualified to repair it, one building at a time. Large sections of neighbourhoods would stay inaccessible for an extended period. [4] [5]

A green placard, meaning the building may be occupied, is not the end of it. “Disruption to water and wastewater systems are expected for many months following the event.” [1] That is the province’s own sentence, and it covers a household whose building was never damaged at all.

A home runs on water, sanitation and electricity. Each comes back on its own schedule, and a household waits on the slowest of the three: a lift needs power, and flushing needs water somebody has to spare.

The figures do not correct each other. The 70,000 counts households in Greater Vancouver, not people and not the province. [1] The two city rows count occupants, inside the City of Vancouver alone. [2]

For Vancouver the rarer magnitude 7.2 crustal earthquake is far worse than the magnitude 9.0 megathrust: about four times the buildings completely or extensively damaged. The reason is shaking at City Hall comparable to the design forces used for new buildings. [2]

Vancouver has about 90,000 buildings. Nearly 70 per cent were built before 1990, when early modern seismic standards arrived, and about half before 1973, before there were any. [2] Five privately owned building types drive nearly 80 per cent of the city’s seismic risk while making up roughly a tenth of the buildings. [2]

The wood-frame apartment building drives more residential displacement than any other type, the detached house included: 64 per cent of its residents are modelled as displaced for more than 90 days in the magnitude 7.2 scenario, which is 45 per cent of the city’s displacement total. [2] Wood-frame houses and wood-frame apartments are different buildings: the apartments are flagged for lack of wall stiffness and strength, and for soft-storey collapse risk where the ground floor is left open for tuck-under parking. [7]

In unreinforced masonry residential buildings, brick walls with no steel in them, over 97 per cent of residents are modelled as displaced for more than 90 days. [2]

Six neighbourhoods carry 65 per cent of the city’s seismic risk: the West End, the Downtown Eastside including Chinatown and Strathcona, Downtown, Kitsilano, Fairview and Mount Pleasant. [2] The census tracts with the highest risk average roughly 70 to 75 per cent renters. [2]

Vancouver publishes 25 disaster support hubs, gathering places that can work outdoors and where group lodging and shelter may be provided depending on impacts. No capacity figure is published for them. [8]

The same strategy lists “Interim housing plans developed” as a condition for moving into recovery, which is work still to be done. [1] And the province wrote it “based on the assumption that First Nations and local authorities are unable to stand up standard emergency response functions, such as emergency support services (ESS), search and rescue (SAR), damage assessment, and shelter for evacuees.” [1]