Photo: Fralambert · CC BY-SA 4.0A quiet place for hazards: low wildfire, little earthquake risk, and 3.9% of tested homes over the radon guideline in Chertsey’s area
Little of the land around Chertsey has burned: 0.1% within 25 km since 1986, or 0.001% a year. Earthquakes add more: NRCan’s model puts building losses at $0.073 a year per $1,000 of value, against $0.030 for the typical town. Hazard risk gives Chertsey a grade of B+; its wildfire band pulls it down.
What stands out about Chertsey’s hazards
Four national sources, each read for Chertsey: earthquakes, radon, past fires and flood studies.
What Chertsey faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Chertsey: B+
Earthquake risk and radon make Chertsey’s grade; wildfire can only lower it, never raise it, and flood studies are listed but not scored.
Its place: #45 of 507 in Quebec and #1,381 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. Only 77 homes were tested in the survey area, so the radon share is rough. Small fires and grass fires are largely missing from the national burned-area record.
Little of the land around Chertsey has burned: 0% within 5 km, 0.1% within 25 km since 1986
Fires mapped since 1986 around where Chertsey’s residents live, and the fuel next to their homes.
Chertsey burns at 0.001% a year, low against 0.000% for the typical Canadian town.
About as much forest grows next to Chertsey’s homes (41% within 5 km) as across 25 km (39%).
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 Quebec · highest of 513
At 0.001% a year, Chertsey ranks 136th of the 513 towns in Quebec; Mistissini leads at 0.31%.
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.
Some fire is mapped around Chertsey, but not enough to leave the low band, where 92% of Canada’s 2,610 towns are; 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.
The flood map inventory lists nothing for Chertsey
Flood studies whose area touches Chertsey, from NRCan’s inventory, each linked to its owner.
The inventory has nothing for Chertsey, but a local or conservation-authority map may still exist.
Towns with a flood study on file
Mapping in Quebec reaches 45% of towns, below the 58% across Canada, and not Chertsey.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Listed, not scored: a flood study proves a map exists, not that Chertsey floods.
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 Chertsey $0.073 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.
Roughly 2.4 times the typical $0.030: Chertsey’s $0.073 marks real seismic exposure.
Shaking damage a year per $1,000 of building value
Earthquake risk in Quebec peaks in La Pocatière ($0.48); Chertsey, at $0.073, is below the median of $0.14.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Chertsey sits above most of Canada’s 2,611 towns on earthquake risk; 28% 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).
The model counts damage to Chertsey’s buildings and their occupants from shaking only: not liquefaction, landslides, tsunami or fires after a quake.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Little radon around Chertsey: 3.9% of area homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Chertsey’s area, at 3.9%, is below the 6.6% of the typical Canadian town, though any one home can still be high.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Against the typical town in Quebec (8.2%), the area around Chertsey has fewer high tests: 3.9%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Under 5% puts Chertsey 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.
The share describes the area, not a house: in Chertsey as anywhere, test to be sure.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Radon tests: one figure for all of the Lanaudiere health region
Weather and fire alerts for Chertsey
Alerts for Chertsey 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. |
Evacuation orders for Chertsey come from the municipality or the province, while CWFIS maps fire danger every day.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Chertsey’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Chertsey | Low | $0.073 | 3.9% | None listed |
| Entrelacs 1,124 · 9.0 km | Low | $0.060 | 3.9% | None listed |
| Rawdon 13,099 · 13 km | Low | $0.085 | 3.9% | None listed |
| Sainte-Marguerite-du-Lac-Masson 3,842 · 14 km | Low | $0.083 | 10% | None listed |
| Saint-Calixte 7,627 · 15 km | Low | $0.091 | 3.9% | None listed |
| Saint-Alphonse-Rodriguez 3,639 · 17 km | Low | $0.067 | 3.9% | None listed |
| Sainte-Julienne 12,990 · 19 km | Low | $0.11 | 3.9% | None listed |
Sainte-Marguerite-du-Lac-Masson burns a little more than Chertsey, 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 Chertsey faces
Practical steps for Chertsey’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?
- Ask the municipality for flood maps.
- 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 Chertsey sits in.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Chertsey’s homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
- 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 Chertsey floods.
- Earthquakes are modelled. Shaking damage is modelled from the ground, the buildings and the odds of each quake, and published for whole subdivisions such as Chertsey’s.
Questions about flooding and hazards in Chertsey
How big is the earthquake risk in Chertsey?
Expected earthquake damage in Chertsey comes to $0.073 a year for each $1,000 that buildings are worth.
Is radon a problem in Chertsey?
The area’s survey found 3.9% of 77 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Chertsey.
Does Chertsey flood?
The inventory has 0 studies for Chertsey, and an empty list isn’t a clean bill: the municipality holds any flood maps.
Is Chertsey at risk of wildfire?
Some, but Chertsey’s low band (0.1% of nearby land burned since 1986, latest 2025) is short of the level that counts.
How is Chertsey’s Hazard risk Grade worked out?
Chertsey’s Hazard risk grade is B+, built on earthquakes and radon with a one-sided wildfire input.
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).