Methodology & Data Sources

Every classification traces to an official public source.

We don't invent a proprietary risk score. Each section of a Parcel Risk Report reports the official categorical hazard zone or class published by a federal or California state agency, labeled by how precisely it applies to the property — so your client knows exactly what's specific to their parcel.

Sources

Where every number comes from

Each hazard is pulled live from the authoritative source below and cited in the report itself.

HazardAuthoritative sourceResolution
Wildfire (FHSZ, incl. AB-38)CAL FIRE / Office of the State Fire Marshal — Fire Hazard Severity Zones (Gov. Code §51178, PRC §4202)Parcel-precise
FloodFEMA National Flood Hazard Layer (NFHL)Parcel-precise
Earthquake fault zoneCalifornia Geological Survey — Alquist-Priolo Earthquake Fault Zones (PRC §2622)Parcel-precise
Seismic hazard zoneCalifornia Geological Survey — Seismic Hazard Zones, liquefaction & landslide (PRC §2696)Parcel-precise
Dam-failure inundationCal OES / California DWR Division of Safety of Dams (DSOD) — inundation maps (Gov. Code §8589.5)Parcel-precise
Seismic Design Category (supplemental — not a probability)USGS Seismic Design Maps (ASCE 7) — building-design ground-motion category, provided as supplemental engineering context, not a statutory NHD determinationPoint estimate
Multi-hazard baselineFEMA National Risk Index (NRI)Census tract
RadonEPA Map of Radon ZonesCounty
Sea-level rise (coastal)NOAA Office for Coastal Management — Sea Level Rise ViewerCoastal segment
Air qualityEPA AirNowPoint estimate
GeocodingU.S. Census Bureau Geocoder (2020 tract vintage)Parcel

The statutory §1103.2 seismic determinations (the Alquist-Priolo fault zone and the seismic hazard zone) are mapped by the California Geological Survey, and the dam-failure inundation determination by Cal OES / DWR DSOD — not USGS. The USGS Seismic Design Category is shown separately as supplemental engineering context (an ASCE 7 building-design category), and is not a probabilistic risk score.

Principles

How we keep it honest

Parcel-precise vs. area-level

Every finding is labeled with its true spatial precision. A county-level radon zone is never presented as a parcel-specific fact — the report tells your client which findings are specific to their property and which are area baselines.

Categorical, not a score

We report the official FEMA flood zone, CAL FIRE severity class, and FEMA NRI rating. We do not publish a personalized probabilistic risk number — those obscure the underlying official classifications.

Current adopted maps

We use the current, adopted hazard maps (for example, the in-effect CAL FIRE Fire Hazard Severity Zones), and each report records the dataset vintage and a source link so any figure can be traced.

Statutory NHD

How this relates to California's statutory NHD

Plain talk about where a Parcel Risk Report fits in a transaction.