Marin County— fire, flood & earthquake hazard information
Marin County is a county in the San Francisco Bay Area, covering about 520.1 square miles. This page summarizes what official government maps show for Marin County: CAL FIRE fire hazard severity zones, FEMA flood zones, state seismic hazard zones, dam inundation areas, airport noise contours, and air-quality indicators. Figures are the share of Marin County’s area that falls inside each mapped zone.
View Marin County on the interactive map → to check any specific address, free.
Wildfire hazard severity zones
Per CAL FIRE's Fire Hazard Severity Zone maps, 2% of Marin County is in a Very High fire hazard severity zone, 7% is in a High zone, 29% is in a Moderate zone. The remainder of its area is outside currently designated zones.
| Very High severity zone | 2% |
| High severity zone | 7% |
| Moderate severity zone | 29% |
FEMA flood zones
7% of Marin County lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO); 3% is in a coastal high hazard zone (V/VE); less than 1% is in the 0.2% annual chance (500-year) area. Federally backed mortgages in a Special Flood Hazard Area generally require flood insurance.
| Special Flood Hazard Area (100-yr) | 7% |
| Coastal high hazard (V/VE) | 3% |
| 0.2% annual chance (500-yr) | less than 1% |
Earthquake faults & seismic zones
The nearest mapped fault, the San Andreas fault zone, is about 4.7 mi (7.6 km) from the center of Marin County. 3 named fault traces in the USGS Quaternary fault database cross its boundary. 2% falls within an Alquist-Priolo earthquake fault zone, where new construction requires a fault study.
| Nearest mapped fault | San Andreas fault zone — 4.7 mi (7.6 km) |
| Named fault traces crossing boundary | 3 |
| Alquist-Priolo fault zone | 2% |
Dam inundation, aircraft noise & air quality
5% of Marin County lies within a state-reviewed dam-failure inundation area; annual average fine-particle (PM2.5) concentration across its census tracts is 7.4 μg/m³, and its composite pollution burden ranks around the 25th percentile statewide.
| Dam-failure inundation area | 5% |
| Annual PM2.5 (tract average) | 7.4 μg/m³ |
| Pollution burden percentile (statewide) | ~25 |
Frequently asked questions
- Is Marin County in a wildfire hazard severity zone?
- Per CAL FIRE's Fire Hazard Severity Zone maps, 2% of Marin County is in a Very High fire hazard severity zone, 7% is in a High zone, 29% is in a Moderate zone. The remainder of its area is outside currently designated zones.
- Is Marin County in a FEMA flood zone?
- 7% of Marin County lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO); 3% is in a coastal high hazard zone (V/VE); less than 1% is in the 0.2% annual chance (500-year) area. Federally backed mortgages in a Special Flood Hazard Area generally require flood insurance.
- What earthquake faults and seismic zones affect Marin County?
- The nearest mapped fault, the San Andreas fault zone, is about 4.7 mi (7.6 km) from the center of Marin County. 3 named fault traces in the USGS Quaternary fault database cross its boundary. 2% falls within an Alquist-Priolo earthquake fault zone, where new construction requires a fault study.
- How do I check a specific address in Marin County?
- Use the free sitelume interactive map at https://sitelume.com — search any Marin County address to see which mapped zones it falls in, layer by layer.
Cities in Marin County
Sources: CAL FIRE Fire Hazard Severity Zones; FEMA National Flood Hazard Layer; USGS Quaternary Faults; CGS Seismic Hazard Zones & Alquist-Priolo zones; Cal OES dam inundation maps; county ALUC noise contours; CalEnviroScreen 4.0. Area shares are computed against each place’s Census TIGER boundary (last computed 2026-07-24). Boundaries and zone designations change; always verify with the issuing agency.