El Sobrante, CA— fire, flood & earthquake hazard information
El Sobrante is a unincorporated community in Contra Costa County in the San Francisco Bay Area, covering about 3.1 square miles. This page summarizes what official government maps show for El Sobrante: 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 El Sobrante’s area that falls inside each mapped zone.
View El Sobrante on the interactive map → to check any specific address, free.
Wildfire hazard severity zones
Per CAL FIRE's Fire Hazard Severity Zone maps, 18% of El Sobrante is in a Very High fire hazard severity zone. The remainder of its area is outside currently designated zones.
| Very High severity zone | 18% |
FEMA flood zones
5% of El Sobrante lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO); 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) | 5% |
| 0.2% annual chance (500-yr) | less than 1% |
Earthquake faults & seismic zones
The Moraga fault crosses El Sobrante. 2 named fault traces in the USGS Quaternary fault database cross its boundary. 25% of its area is in a state-designated liquefaction zone of required investigation. 10% is in an earthquake-induced landslide zone. 2% falls within an Alquist-Priolo earthquake fault zone, where new construction requires a fault study.
| Nearest mapped fault | Moraga fault — 0.0 mi (0.0 km) |
| Named fault traces crossing boundary | 2 |
| Liquefaction zone | 25% |
| Earthquake-induced landslide zone | 10% |
| Alquist-Priolo fault zone | 2% |
Dam inundation, aircraft noise & air quality
38% of El Sobrante lies within a state-reviewed dam-failure inundation area; annual average fine-particle (PM2.5) concentration across its census tracts is 8.9 μg/m³, and its composite pollution burden ranks around the 27th percentile statewide.
| Dam-failure inundation area | 38% |
| Annual PM2.5 (tract average) | 8.9 μg/m³ |
| Pollution burden percentile (statewide) | ~27 |
Frequently asked questions
- Is El Sobrante in a wildfire hazard severity zone?
- Per CAL FIRE's Fire Hazard Severity Zone maps, 18% of El Sobrante is in a Very High fire hazard severity zone. The remainder of its area is outside currently designated zones.
- Is El Sobrante in a FEMA flood zone?
- 5% of El Sobrante lies within a FEMA Special Flood Hazard Area (1% annual chance, zones A/AE/AH/AO); 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 El Sobrante?
- The Moraga fault crosses El Sobrante. 2 named fault traces in the USGS Quaternary fault database cross its boundary. 25% of its area is in a state-designated liquefaction zone of required investigation. 10% is in an earthquake-induced landslide zone. 2% falls within an Alquist-Priolo earthquake fault zone, where new construction requires a fault study.
- How do I check a specific address in El Sobrante?
- Use the free sitelume interactive map at https://sitelume.com — search any El Sobrante address to see which mapped zones it falls in, layer by layer.
Nearby in Contra Costa 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.