Photo: Loozrboy from Toronto, Canada · CC BY-SA 2.0Hazard risk in Greensborough is lower than in 88% of Canadian towns
Since 1986 almost nothing has burned near Greensborough: 0% of the land within 25 km, or 0.000% a year. For earthquakes Greensborough is middling, $0.034 a year per $1,000 against $0.030 for the typical town. In Health Canada’s survey, just 0% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). Greensborough grades A for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Greensborough’s hazards
For Greensborough, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Greensborough faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Greensborough: A
For Greensborough, Risk will be the average of earthquakes and radon, with wildfire added only if it makes the average worse.
Its place: #165 of 866 in Ontario and #484 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 Greensborough: 0% of the land within 25 km burned since 1986, 0% within 5 km
Past fire around Greensborough’s homes, from the national burned-area record, with the fuel within 5 km.
Greensborough burns at 0.000% a year, low against 0.000% for the typical Canadian town.
The closest burn since 1986 lies 8.2 km from Greensborough’s homes, none within 5 km.
8.9% of the land within 25 km of Greensborough is forest fuel, yet only 2.2% within 5 km of its homes.
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
Sioux Lookout has the highest burn rate in Ontario, 0.16% a year; around Greensborough, as around 638 of the 871 towns, it rounds to 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.
Like most of Canada’s 2,610 towns (92%), Greensborough 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.
Greensborough is on the flood map inventory: 2 studies, latest by Toronto Regional Conservation Authority
What Canada’s Flood Map Inventory lists for Greensborough: who studied flooding and where to see their maps.
The newest of 2 studies covering Greensborough is Toronto Regional Conservation Authority’s, from 2021; open its map to see the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Toronto Floodline Consolidation | Toronto Regional Conservation Authority | 2021 | final |
| Duffins Creek | Toronto and Region Conservation Authority | 2020 | final |
Towns with a flood study on file
Flood maps are common in Ontario: 69% of towns have one, against 58% nationally, and Greensborough is among them.
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 Greensborough 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.
Ordinary seismic risk in Greensborough: $0.034 per $1,000 of buildings a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
1.1 times the typical $0.030: Greensborough’s $0.034 is ordinary.
Shaking damage a year per $1,000 of building value
Below the middle in Ontario: Greensborough’s $0.034 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.
Around half of Canada’s 2,611 towns expect more shaking damage than Greensborough (46%).
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 Greensborough 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). · Earthquake risk: the city of Markham
0% of homes tested around Greensborough are over the radon guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Area-wide: radon tests, counted over the York Regional Health Unit
Radon runs below the typical Canadian town (6.6%) in Greensborough’s area, at 0%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Greensborough’s area, at 0%, is below the median in Ontario (4%).
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Few tests over the guideline: Greensborough shares the bottom band with 37% of Canada’s 2,611 towns, below the other 63%.
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.
Radon varies from house to house in Greensborough, so the survey is a reason to test, not a result for yours.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Greensborough
Alerts for Greensborough 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 Greensborough to phones; CWFIS shows the day’s fire danger.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Greensborough’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 |
|---|---|---|---|---|
| Greensborough | Low | $0.034 | 0% | Yes |
| Mount Joy 8,345 · 1.2 km | Low | $0.034 | 0% | Yes |
| Wismer Commons 20,591 · 1.8 km | Low | $0.034 | 0% | Yes |
| Upper Cornell 8,304 · 1.8 km | Low | $0.034 | 0% | Yes |
| Markham Village 10,319 · 1.9 km | Low | $0.034 | 0% | Yes |
| Cornell 22,014 · 2.5 km | Low | $0.034 | 0% | Yes |
| Quantztown 13,146 · 3.4 km | Low | $0.034 | 0% | Yes |
Mount Joy burns a little more than Greensborough, 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 Greensborough faces
Practical steps for Greensborough’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. Health Canada’s survey tested some 14,000 homes over three months; until postal-area boundaries are loaded, Greensborough takes its 2007 health region’s share.
- Wildfire counts one way. For Greensborough, wildfire means how much nearby land burned in the past forty years, a one-way input that can pull Risk down and nothing more.
- Earthquakes are modelled. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Greensborough’s census subdivision (a neighbourhood shows its city’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 Greensborough.
Questions about flooding and hazards in Greensborough
How big is the earthquake risk in Greensborough?
In NRCan’s seismic model, Greensborough’s buildings lose $0.034 per $1,000 of value in an average year.
Does Greensborough flood?
The inventory lists a study touching Greensborough; whether a given street floods is on that map, not in the grade.
How is Greensborough’s Hazard risk Grade worked out?
Greensborough grades A for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Is Greensborough at risk of wildfire?
Some, but Greensborough’s low band (0% of nearby land burned since 1986, latest 2001) is short of the level that counts.
Is radon a problem in Greensborough?
The area’s survey found 0% of 95 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Greensborough.
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).