Photo: davestew89 · CC BY 3.0Hazards in Marathon: wildfire low, radon over the guideline in 12% of tested homes
Wildfire isn’t Marathon’s worry: 0% of the land within 25 km burned since 1986 (0.000% a year). Seismic risk runs low: $0.003 of expected damage per $1,000 of buildings a year, the typical town $0.030. Marathon grades A− for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Marathon’s hazards
For Marathon, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Marathon faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Marathon grades A− for hazard risk
Risk averages earthquakes and radon; wildfire joins only where it pulls the average down, so a town like Marathon with little fire nearby would get no credit for it.
Its place: #277 of 866 in Ontario and #657 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Wildfire is rare near Marathon: 0% of the land within 25 km burned since 1986, 0% within 5 km
Fires mapped since 1986 around where Marathon’s residents live, and the fuel next to their homes.
With 0.000% burned a year, Marathon is among the many low-band places (the typical Canadian town 0.000%).
The closest burn since 1986 lies 14 km from Marathon’s homes, none within 5 km.
The nearer ring around Marathon is less wooded (61% forest fuel) than the land out to 25 km (72%).
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
Among the 871 towns in Ontario, Sioux Lookout burns fastest (0.16% a year); Marathon is with the 638 near zero.
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.
Most of the country’s 2,610 towns are low-band (92%, against 7.5% above); around Marathon, burning rounds to zero.
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.
No flood study is listed for Marathon
Flood studies whose area touches Marathon, from NRCan’s inventory, each linked to its owner.
No flood study on the national inventory covers Marathon; ask the municipality, which is the authority for its flood maps.
Towns with a flood study on file
Flood maps are common in Ontario, 69% of towns against 58% nationally, but none in the inventory touches Marathon.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Nothing here counts toward Risk; the studies are pointers to the maps their owners keep for Marathon.
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.”
Earthquakes cost buildings in Marathon just $0.003 per $1,000 a year
NRCan’s seismic risk model: the damage shaking is expected to do to buildings each year, on average over many years.
0.1 times the typical $0.030: Marathon’s $0.003 is low for Canada.
Shaking damage a year per $1,000 of building value
Below the middle in Ontario: Marathon’s $0.003 against a median of $0.043; Alexandria has $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.
At the bottom of Canada’s range, Marathon has 99% of the 2,611 towns above it.
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).
For Marathon the model prices shaking damage to buildings, nothing more.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
12% of homes tested around Marathon are over the radon guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline. · Shared with the rest of the Thunder Bay District Health Unit: radon tests
A higher share than most: 12% of tested homes around Marathon, the typical Canadian town 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
More homes top the guideline around Marathon (12%) than in the typical town in Ontario (4%); 0.9% went over 600.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
The 10–20% band holds 22% of Canada’s 2,611 towns, Marathon among them; 4.6% rank above.
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.
Health Canada advises testing every home, Marathon’s included, whatever the area’s figure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Marathon
Environment and Climate Change Canada issues the weather alerts for Marathon; Alert Ready carries the urgent ones to phones, radio and TV.
| 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. |
In fire season, check CWFIS for danger and active fires around Marathon, and listen to local authorities for orders.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Get ready for what Marathon faces
What to do about the hazards Marathon faces, and what to ask before you buy.
- 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?
- Ask the municipality for flood maps.
- Are flood and wildfire insured?
What this data can and can’t tell you
- Earthquakes are modelled. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Marathon’s census subdivision (a neighbourhood shows its city’s).
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Marathon is its health region’s, the survey’s design unit.
- Flood studies aren’t flood zones. NRCan’s inventory says where flood mapping exists, not where water goes; the map’s owner is the authority for Marathon.
- Wildfire counts one way. For Marathon, wildfire means how much nearby land burned in the past forty years, a one-way input that can pull Risk down and nothing more.
Questions about flooding and hazards in Marathon
How big is the earthquake risk in Marathon?
About $0.003 a year per $1,000 of building value, NRCan’s long-run expectation for Marathon.
Does Marathon flood?
With 0 studies on the inventory, Marathon’s flood risk is unmapped nationally; check with the municipality before buying.
How is Marathon’s Hazard risk Grade worked out?
Hazard risk gives Marathon A−, weighing earthquakes and radon and counting wildfire only against it.
Is Marathon at risk of wildfire?
Fire has reached 0% of the land around Marathon since 1986 (last in 2012); at low, it neither helps nor hurts the grade.
Is radon a problem in Marathon?
Around Marathon, 108 survey homes were tested and 12% came in over 200 Bq/m³, a guide to the area, not to any one home.
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).