GeraSure / County Hazard Risk / Rock, WI
Rock County, Wisconsin: Natural Hazard Risk
Gera County Hazard Score: 55.7/100 (Moderate) · FEMA Rating: Relatively Low · Population: 163,608. Based on FEMA National Risk Index (November 2023).
What is the natural hazard risk for Rock County, Wisconsin?
Rock County, Wisconsin has a Gera County Hazard Score (GCHS) of 55.7/100 (Moderate), based on FEMA National Risk Index November 2023 data. Its Expected Annual Loss rank is 81.8/100, social vulnerability rank 42.8/100 and community resilience rank 90.4/100, covering a population of 163,608.
GCHS components — Rock County (November 2023)
| Component | Score / 100 | GCHS Weight | Contribution | What it measures |
|---|---|---|---|---|
| Expected Annual Loss (EAL) | 81.8 | 50% | 40.9 | Estimated annual losses from 18 natural hazards |
| Social Vulnerability (SOVI) | 42.8 | 30% | 12.8 | Community factors affecting disaster response capacity |
| Lack of Resilience (100 − RESL) | 10 | 20% | 1.9 | Resilience score 90.4/100 → inverted so higher = more hazard |
| Gera County Hazard Score (GCHS) | 55.7 | 100% | 55.7 | Moderate — composite index |
GCHS = 0.50 × 81.8 + 0.30 × 42.8 + 0.20 × (100 − 90.4) = 55.7. All inputs are FEMA NRI percentile ranks 0–100.
Rock County Hazard Checker
Explore what the GCHS means for insurance and disaster preparedness in this county.
Gera County Hazard Score (GCHS)
What this means for insurance
A Moderate GCHS suggests mixed risk. Standard policies generally cover you, but flood or earthquake riders may be worth considering.
GCHS is computed by Gera from FEMA NRI data. It is a risk-context index — not an insurance premium quote. Actual premiums depend on your specific property and chosen coverage.
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Rock County hazard risk: frequently asked questions
- What does a GCHS of 55.7/100 mean for Rock County?
- A GCHS of 55.7/100 places Rock County in the "Moderate" band. This is a moderate risk level. Standard insurance policies generally cover the main hazards, but it is worth reviewing coverage for the specific hazard types that affect this area.
- Which natural hazards most affect Rock County?
- The GCHS is computed from FEMA's Expected Annual Loss (EAL) score, which aggregates 18 natural hazard types: hurricanes, riverine flooding, tornadoes, wildfires, earthquakes, hail, drought, winter weather, lightning, strong wind, coastal flooding, cold wave, heat wave, ice storm, landslide, avalanche, tsunami and volcanic activity. Rock County's EAL rank is 81.8/100 — very high, suggesting substantial exposure to one or more of these hazards.
- What is the FEMA National Risk Index?
- The FEMA National Risk Index (NRI) is a publicly available dataset produced by the US Federal Emergency Management Agency that measures the risk of natural hazards for every US county and census tract. It combines 18 natural hazard types, community social vulnerability and community resilience into a single expected-loss-based risk score. Gera computes the GCHS from the NRI's county-level EAL, SOVI and RESL percentile scores using a documented formula.
- How does Rock County compare to the national average?
- The national mean GCHS across the 480 most-populous US counties is 66.1/100. Rock County scores 55.7/100, which is 10.4 points below the national mean. FEMA's own risk rating for this county is "Relatively Low".
Other WI counties
All counties →Contains public sector information published by Federal Emergency Management Agency (FEMA) and licensed under the US Government open data, public domain. Source: FEMA National Risk Index (NRI) — Harvard Dataverse (November 2023, published 2024).
Full GCHS formula and verification: Gera County Hazard Score methodology.