Photo: P199 · CC BY-SA 3.0Flood mapping exists for Petrolia: 1 on record, latest by St. Clair Region Conservation Authority
The burned-area map is nearly blank around Petrolia, 0% within 25 km since 1986, 0.000% a year. Seismic risk runs low: $0.015 of expected damage per $1,000 of buildings a year, the typical town $0.030. Petrolia’s survey area, 8.4% over the radon guideline, is close to the typical town’s 6.6%. Hazard risk gives Petrolia a grade of B+, from earthquakes and radon alone.
What stands out about Petrolia’s hazards
Four national sources, each read for Petrolia: earthquakes, radon, past fires and flood studies.
What Petrolia faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Petrolia: B+
Earthquake risk and radon make Petrolia’s grade; wildfire can only lower it, never raise it, and flood studies are listed but not scored.
Its place: #478 of 866 in Ontario and #926 of 2,589 Canadian towns.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. Small fires and grass fires are largely missing from the national burned-area record.
Wildfire is rare near Petrolia: 0% of the land within 25 km burned since 1986, 0% within 5 km
Fires mapped since 1986 around where Petrolia’s residents live, and the fuel next to their homes.
The land within 25 km of Petrolia burns at 0.000% a year on average, the low band; the typical Canadian town: 0.000%.
Around Petrolia the forest is thin or far off: 0.1% of the land within 5 km and 0.2% within 25 km is forest fuel.
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
Near-zero burning puts Petrolia with 638 of the 871 towns in Ontario, far below Sioux Lookout at 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.
Measured against 2,610 towns, Petrolia is in the largest group, low (92%), and at its floor, while 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.
St. Clair Region Conservation Authority has mapped flooding for Petrolia (1 study)
Flood studies whose area touches Petrolia, from NRCan’s inventory, each linked to its owner.
St. Clair Region Conservation Authority holds the flood mapping that covers Petrolia (2009), linked below.
| Study | By | Year | Status |
|---|---|---|---|
| SCRCA Floodplain Estimation Study for Ontario Regulation 171-06 | St. Clair Region Conservation Authority | 2009 | final · not public |
Towns with a flood study on file
Its flood study puts Petrolia with 69% of towns in Ontario; Canada’s share is 58%.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood mapping is shown for Petrolia to be opened and checked, never turned into a grade.
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.
Earthquakes cost buildings in Petrolia just $0.015 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.
Shaking costs the typical town $0.030 a year; in Petrolia it is only $0.015, 0.5 times as much.
Shaking damage a year per $1,000 of building value
At $0.015, Petrolia 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.
Earthquakes cost less around Petrolia than in 72% of Canada’s 2,611 towns.
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).
Roads, pipes and bridges aren’t in Petrolia’s figure, nor landslides or tsunami: it is buildings and shaking.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Radon about average around Petrolia: 8.4% over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Around Petrolia, 8.4% of tested homes topped the guideline, near the typical Canadian town’s 6.6%. Figures for radon tests are published for the Lambton Health Unit as a whole, not for Petrolia alone.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
More homes top the guideline around Petrolia (8.4%) than in the typical town in Ontario (4%); 0.6% went over 600.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Between 5% and 10% of tests over the guideline: Petrolia, and 37% of Canada’s 2,611 towns; 26% are higher.
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.
Basements, soil and how a house is sealed decide its radon, so in Petrolia only a test can say.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Petrolia
Alerts for Petrolia 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. |
Alert Ready carries evacuation orders for Petrolia to phones; CWFIS shows the day’s fire danger.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Petrolia’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Petrolia | Low | $0.015 | 8.4% | Yes |
| Enniskillen 3,174 · 2.1 km | Low | $0.017 | 8.4% | Yes |
| Plympton-Wyoming 9,548 · 13 km | Low | $0.014 | 8.4% | Yes |
Among its neighbours Petrolia has the most fire on record (low); Enniskillen follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Petrolia faces
Practical steps for Petrolia’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
- Wildfire counts one way. Wildfire is read from the national burned-area record around Petrolia’s homes since 1986, a history of fire that may lower Risk but never raises it.
- Earthquakes are modelled. NRCan models what earthquakes would cost buildings each year on average, subdivision by subdivision; Petrolia’s figure is its subdivision’s.
- Flood studies aren’t flood zones. The flood inventory points to maps; it is incomplete and not the official source, so ask the municipality about any street in Petrolia.
- Radon is a survey. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, Petrolia takes its 2007 health region’s share.
Questions about flooding and hazards in Petrolia
Is Petrolia at risk of wildfire?
Hardly at all on record: 0% of the land within 25 km of Petrolia since 1986, a low band, though small grass fires aren’t mapped.
Does Petrolia flood?
The inventory lists a study touching Petrolia; whether a given street floods is on that map, not in the grade.
How big is the earthquake risk in Petrolia?
About $0.015 a year per $1,000 of building value, NRCan’s long-run expectation for Petrolia.
How is Petrolia’s Hazard risk Grade worked out?
Petrolia’s Hazard risk grade is B+, built on earthquakes and radon with a one-sided wildfire input.
Is radon a problem in Petrolia?
The area’s survey found 8.4% of 178 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Petrolia.
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).