Fire, flood, quake and storm: Canada's natural hazards

The Red River Floodway inlet, just south of Winnipeg, in April. Nadia Petrenko is 33, from Ukraine, a civil-engineering technologist who arrived in 2022. She is standing on the control structure, the gates that can send the Red River's spring flood around the city instead of through it. Since her first week here she has wondered why her adopted city dug a ditch this size. This lecture is the answer.

So here's the question. Where do Canada's natural hazards sit on the map, and why there? Fire, flood, earthquake and storm each have an address. One note first: this lecture describes disasters, and there are no graphic images in it.

Fire. In 2023 Canada burned somewhere between 15 and 18.5 million hectares, depending on whether you count the fire perimeters reported by the agencies or the ground the satellites actually saw blackened. Natural Resources Canada's figure is 15 million: an area bigger than England, more than double the old record from 1989, and about six times a normal year.

Flood. Manitoba's flood history: the Red River put 100,000, a third of Winnipeg, out of their homes in 1950. In 1997, over 25,000 were evacuated, and without the Floodway the crest would have run about three metres higher. Calgary, 2013: about 80,000 evacuated. British Columbia, November 2021: up to 300 millimetres of rain in about two days, at least six deaths.

Earthquake. Natural Resources Canada counts more than 4,000 a year, most on the British Columbia coast, including a magnitude 8.1 off Haida Gwaii in 1949. The Cascadia zone is locked: great quakes there come every 300 to 800 years, and the last was in January 1700. Storm. Hurricane Fiona, September 2022: 932.7 hectopascals, the deepest pressure ever recorded over land in Canada.

Find it on the map. This is Natural Resources Canada's seismic hazard map, shaded from pale to dark by how strong the shaking is likely to be. The darkest shading hugs the British Columbia coast and Haida Gwaii. That is Cascadia. But look east: a second, fainter patch runs up the Ottawa and St. Lawrence valleys, and another sits off southern Newfoundland. A hazard map shows where. The history shows how often.

Let's change one fact. Slide the Cascadia plate boundary under Winnipeg. Manitoba would become the earthquake province, and Nadia's Floodway would have to survive shaking as well as water. In reality, Natural Resources Canada says Manitoba has the fewest earthquakes of any province: old, stable crust, far from any plate edge. The river is Winnipeg's hazard. The ground under it is a gift.

The mistake people make is saying earthquakes don't happen in Canada, or only out west. Natural Resources Canada lists the Ottawa and St. Lawrence valleys, New Brunswick and the waters south of Newfoundland as earthquake zones, along with the West Coast and the North. Most are small, and few are felt. But the map is not blank east of the Rockies.

Here's the rule, in one breath. Fire where the forest is dry, flood where the rivers are flat, quakes where the plates meet, storms where the Atlantic comes ashore; the map shows where, the history shows how often.

This week, find your community on the Earthquakes Canada seismic hazard map, then find your municipality's flood map, and learn the one hazard that is actually yours. Not all of them. The one. Then find out how you would get the warning, and where you would go.

Next time, a new module, and the people: just over 41 million of us, and where we are.