Casualties

The City of Vancouver reports casualties as a single count, at two times of day. The province splits its figures four ways, into the dead, the critically injured, those needing hospital care and those needing first aid.

The method behind the City’s assessment has been published and peer reviewed. [5]

They nearly all trace back to the Geological Survey of Canada’s scenario catalogue, which counts “only damage to buildings, and their inhabitants, from earthquake shaking”. [6] In the open file behind the province’s planning scenario, aftershocks, tsunami, landslides, liquefaction “and fire following are not considered”, and neither is damage to vehicles or infrastructure. [3] Natural Resources Canada draws the conclusion itself, about its own work: “therefore, the estimates herein are likely to represent a minimum estimate on impacts.” [3]

The province says the same of its own numbers. They rest on damage to buildings and “do not include casualties from other secondary hazards or complicating factors”, a list running through underlying medical conditions, vehicle accidents, falls, explosions, fires, landslides, washouts and tsunamis. The strategy “will not consider the effect of an earthquake early warning system”, and the data is “for planning purposes only and may not match the outcome of real events”. [2] Its Cascadia figures carry the same limit: they “include only direct mainshock damage without account of secondary hazards like landslides, liquefaction, tsunami, fires and more.” [4]

So every one of these counts is a floor. Fires, landslides and liquefaction hurt people too, and none of these models was asked to count them.

Intuition says the largest earthquake does the most harm. In the City’s own modelling it does not. The crustal earthquake in the Strait of Georgia gives more than three times the daytime casualties in the city that the Cascadia earthquake offshore does, and it shakes City Hall about as hard as the design forces new buildings are built to resist. [1]

In both of the City’s scenarios the night figure is under half the daytime one. [1] What changes is where people are. At night they are at home; through the working day they are in offices, schools, shops and on the street.

The province’s magnitude 7.0 scenario is set on a weekday between 9 am and 5 pm, “when most people are at school or work”, and every casualty figure in it belongs to that hour of the day. [3] Its Cascadia scenario puts the mainshock at 10 am on a day in August. [4]

Concrete mid-rise and high-rise residential buildings, concentrated in the West End and Downtown, account for 37 per cent of the night-time casualties in the magnitude 7.2 earthquake. Unreinforced masonry residential buildings in Gastown, the Downtown Eastside and Chinatown account for a further 29 per cent, from 581 buildings holding about 24,700 residents. [1] Unreinforced masonry is brick or concrete block built without steel reinforcing.

What each building type does in the shaking, and how much of it Vancouver has, is set out under buildings.

In the 2011 earthquake in Christchurch, New Zealand, building failure killed 42 people apart from the two office buildings that collapsed. Of those, 35 died when unreinforced masonry façades or walls fell, and 26 of the 35 were struck in the street or in vehicles. [7]

That is Christchurch, and it sets no figure for anywhere here. What it shows is where the danger sits during the shaking: at the edge of the building, on the footpath, where the wall lands. The province’s magnitude 7.0 scenario says the same: “Many of those who try to run outside suffer extreme injury or death from falling and flying objects”. [2]

The Conference Board of Canada published a study in 2016 of what a major earthquake would do to Canada’s economy, with funding from the Insurance Bureau of Canada. A figure of approximately 15,000 deaths is often quoted from it. [8] The report’s own words: “An assumption was made that this earthquake would result in approximately 15,000 deaths”. The Board reasoned it up from the province’s own planning figures, then reduced Canada’s population by that number inside its economic model. [9]

Nothing about the figure was measured. It was chosen as an input, and the model was run with Canada’s population reduced by it.