Alum Rock, CA— fire, flood & earthquake hazard information
Alum Rock is a unincorporated community in Santa Clara County in the San Francisco Bay Area, covering about 0.9 square miles. This page summarizes what official government maps show for Alum Rock: 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 Alum Rock’s area that falls inside each mapped zone.
View Alum Rock on the interactive map → to check any specific address, free.
Wildfire hazard severity zones
CAL FIRE's current Fire Hazard Severity Zone maps do not designate any zones within Alum Rock. Individual properties near the boundary can still fall inside a neighboring zone — check the exact address on the map.
FEMA flood zones
FEMA's National Flood Hazard Layer does not map any Special Flood Hazard Areas within Alum Rock. Unmapped does not mean flooding cannot occur — it means no zone is currently designated.
Earthquake faults & seismic zones
The nearest mapped fault, the Hayward fault zone, is about 0.5 mi (0.8 km) from the center of Alum Rock. 1 named fault trace in the USGS Quaternary fault database cross its boundary. less than 1% of its area is in a state-designated liquefaction zone of required investigation.
| Nearest mapped fault | Hayward fault zone — 0.5 mi (0.8 km) |
| Named fault traces crossing boundary | 1 |
| Liquefaction zone | less than 1% |
Dam inundation, aircraft noise & air quality
annual average fine-particle (PM2.5) concentration across its census tracts is 8.5 μg/m³, and its composite pollution burden ranks around the 7th percentile statewide.
| Annual PM2.5 (tract average) | 8.5 μg/m³ |
| Pollution burden percentile (statewide) | ~7 |
Frequently asked questions
- Is Alum Rock in a wildfire hazard severity zone?
- CAL FIRE's current Fire Hazard Severity Zone maps do not designate any zones within Alum Rock. Individual properties near the boundary can still fall inside a neighboring zone — check the exact address on the map.
- Is Alum Rock in a FEMA flood zone?
- FEMA's National Flood Hazard Layer does not map any Special Flood Hazard Areas within Alum Rock. Unmapped does not mean flooding cannot occur — it means no zone is currently designated.
- What earthquake faults and seismic zones affect Alum Rock?
- The nearest mapped fault, the Hayward fault zone, is about 0.5 mi (0.8 km) from the center of Alum Rock. 1 named fault trace in the USGS Quaternary fault database cross its boundary. less than 1% of its area is in a state-designated liquefaction zone of required investigation.
- How do I check a specific address in Alum Rock?
- Use the free sitelume interactive map at https://sitelume.com — search any Alum Rock address to see which mapped zones it falls in, layer by layer.
Nearby in Santa Clara 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.