Photo: norgo · CC BY-SA 3.0Hazard risk in Severn is lower than in 94% of Canadian towns
The burned-area map is nearly blank around Severn, 0% within 25 km since 1986, 0.000% a year. Shaking is about as much of a worry in Severn as in most places, at $0.019 a year per $1,000 of building value ($0.030 typical). Fewer homes than usual carry radon here, 0.9% over the guideline where the typical town has 6.6%. Hazard risk gives Severn a grade of A, from earthquakes and radon alone.
What stands out about Severn’s hazards
For Severn, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Severn faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Severn grades A for hazard risk
Seismic risk and radon set Severn’s grade, wildfire can drag it down, and flood mapping stays out of it.
Its place: #21 of 866 in Ontario and #263 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Few fires near Severn: 0% within 5 km, 0% within 25 km
Past fire around Severn’s homes, from the national burned-area record, with the fuel within 5 km.
The yearly burn rate around Severn is 0.000%, low beside 0.000% for the typical Canadian town.
Since 1986 the nearest fire to Severn’s homes came within 11 km, never inside 5 km.
Near or far, forest fuel covers a similar share around Severn: 20% within 5 km and 24% within 25 km.
Shares of land within 5 and 25 km of populated blocks: burned at least once in 1986–2025 (CWFIS burned-area composite), forest fuel and grass (fire behaviour fuel types, 2026, 250 m grid).
Burn rate a year, towns in Ontario · highest of 871
To three decimals the burn rate around Severn is zero, as for 638 of the 871 towns in Ontario, while Sioux Lookout reaches 0.16%.
Each bar: the yearly average share of land within 25 km of a town’s homes that burned, 1986–2025 (CWFIS); the seven highest towns of 2,500 people or more.
Like most of Canada’s 2,610 towns (92%), Severn is in the low band, with a burn rate of zero to three decimals; 7.5% rank higher.
Bands of the yearly burn rate: low under 0.05%, moderate under 0.25%, high under 1%, very high 1% or more; towns of 2,500 people or more.
Fire danger and active fires (CWFIS)
Canadian Wildland Fire Information System: National Burned Area Composite 1986–2025 and fire behaviour fuel types (2026), Natural Resources Canada. Measured within 25 km and 5 km of each populated dissemination area; past fire, not a forecast.
District Municipality of Muskoka has mapped flooding for Severn (1 study)
What Canada’s Flood Map Inventory lists for Severn: who studied flooding and where to see their maps.
For Severn the inventory points to District Municipality of Muskoka’s 2024 study, whose map is the one to check.
| Study | By | Year | Status |
|---|---|---|---|
| District of Muskoka Floodplain Mapping | District Municipality of Muskoka | 2024 | final |
Towns with a flood study on file
69% of towns in Ontario have a flood study, more than Canada’s 58%; Severn has one too.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood studies don’t enter the grade; they are listed so you can open the official map for Severn.
The inventory’s own caution (NRCan): “The Canada Flood Map (CFM) does not include every flood hazard map in Canada and may be incomplete or contain inaccuracies. It should not be relied upon as the official source of flood mapping information. Furthermore, if a map appears to be missing, this does not necessarily mean that the area has never been mapped. For the official version of a map, updated information, or confirmation of applicable regulations, please contact the local authority responsible for flood mapping.”
Natural Resources Canada, Canada Flood Map Inventory; links go to each study’s owner.
Ordinary seismic risk in Severn: $0.019 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Severn’s $0.019 is close to the typical town’s $0.030 (0.6 times as much).
Shaking damage a year per $1,000 of building value
At $0.019, Severn is below the typical town in Ontario ($0.043); Alexandria is highest at $0.21.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Severn is in the lower part of Canada’s range for earthquake risk; 66% of the 2,611 towns are higher.
Each column: the share of Canada’s towns of 2,500 people or more in that range of yearly loss per $1,000 (NRCan, 2022).
What a quake does after the shaking, fire, landslides, tsunami, falls outside NRCan’s figure for Severn.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Radon runs low around Severn: 0.9% of tested homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
Severn’s area, at 0.9%, is below the 6.6% of the typical Canadian town, though any one home can still be high. Severn shares its radon tests numbers with the rest of the Simcoe Muskoka District Health Unit.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Against the typical town in Ontario (4%), the area around Severn has fewer high tests: 0.9%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Under 5% puts Severn with 37% of Canada’s 2,611 towns; 63% have more high tests.
Each bar: the share of Canada’s towns of 2,500 people or more whose survey area had that share of tests over 200 Bq/m³.
Neighbouring homes in Severn can differ a lot; only a long-term test tells you about yours.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Severn
Alerts for Severn come from Environment and Climate Change Canada and, for emergencies, Alert Ready.
| Alert | What it means |
|---|---|
| Warning | Severe weather is happening or about to: act now. |
| Watch | Conditions favour severe weather: be ready. |
| Advisory | Weather that is less severe but could disrupt the day. |
| Special weather statement | Unusual weather worth knowing about. |
| Special air quality statement | Poor air, often wildfire smoke. |
Fire danger and active fires near Severn are mapped daily by the Canadian Wildland Fire Information System; evacuation orders come from the municipality or province.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Severn’s neighbours compare on hazards
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Severn | Low | $0.019 | 0.9% | Yes |
| Orillia 37,735 · 7.1 km | Low | $0.019 | 0.9% | Yes |
| Chippewas of Rama First Nation 1,149 · 8.7 km | Low | $0.028 | 0.9% | Yes |
| Oro-Medonte 24,681 · 17 km | Low | $0.015 | 0.9% | Yes |
| Ramara 11,551 · 18 km | Low | $0.026 | 0.9% | Yes |
Orillia burns a little more than Severn, in the same low band (low here).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Severn faces
Practical steps for Severn’s hazards, most pressing first.
- Test for three months in winter.
- Over 200 Bq/m³: fix it.
- Kits are cheap; pros test too.
- Never drive through floodwater.
- Move papers and medicines upstairs.
- Ask whether your street is mapped.
- Clear needles and wood nearby.
- Keep a grab-and-go bag ready.
- In smoke, stay in; filter air.
- Has it had a radon test?
- Check the address on the flood map.
- Are flood and wildfire insured?
What this data can and can’t tell you
- Radon is a survey. The radon share comes from about 14,000 long-term home tests in 2009–2011, pooled for now by the 2007 health region Severn sits in.
- Earthquakes are modelled. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Severn’s included.
- Flood studies aren’t flood zones. A study’s area can be a whole watershed or province, so being on the inventory says a map exists, not that a home in Severn floods.
- Wildfire counts one way. Burned land within 25 km of where people live, averaged over 1986–2025 and checked for fuel near homes, is the measure; it looks back, not ahead, and only ever counts against Severn.
Questions about flooding and hazards in Severn
How big is the earthquake risk in Severn?
In NRCan’s seismic model, Severn’s buildings lose $0.019 per $1,000 of value in an average year.
Is radon a problem in Severn?
The area’s survey found 0.9% of 109 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Severn.
How is Severn’s Hazard risk Grade worked out?
Severn’s Hazard risk grade is A, built on earthquakes and radon with a one-sided wildfire input.
Does Severn flood?
Severn’s area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
Is Severn at risk of wildfire?
Some, but Severn’s low band (0% of nearby land burned since 1986, latest 2016) is short of the level that counts.
Seismic risk: Natural Resources Canada. Radon: Health Canada. Wildfire: Canadian Wildland Fire Information System. Flood studies: Natural Resources Canada, Canada Flood Map Inventory. Contains information licensed under the Open Government Licence – Canada.
Sources: NRCan, Canada’s Seismic Risk Model 2022 · Health Canada, Cross-Canada Survey of Radon Concentrations in Homes · CWFIS, National Burned Area Composite and FBP fuel types · NRCan, Canada Flood Map Inventory. Under the Statistics Canada Open Licence.
Adapted from Statistics Canada (Census of Population 2021, population estimates 2025, 2021 census boundaries) under the Statistics Canada Open Licence; this does not constitute an endorsement by Statistics Canada. Neighbourhood names in some cities © OpenStreetMap contributors (ODbL).