About
Earthquake
Earthquake results are FEMA National Risk Index values for the county, not a site-specific shaking model. The headline is the expected annual loss rating (for example, Relatively Moderate), not the composite earthquake risk rating that also folds in social vulnerability and community resilience. Frequency comes from the NRI annualized frequency field. Event counts, when present, are from the NRI record, which FEMA treats as a 100-year earthquake history for this index.
Peak ground acceleration comes from the USGS National Seismic Hazard Model at the address, for a 2% chance of exceedance in 50 years on site class BC (Vs30 = 760 m/s). Instrumental intensity and potential damage follow the USGS ShakeMap PGA ranges (Wald et al. 1999).
| Category | Magnitude | Expected damage |
|---|---|---|
| Micro | Less than 2.0 | Not felt. No property damage. |
| Minor | 2.0–3.9 | Often felt nearby. Damage is rare. |
| Light | 4.0–4.9 | Noticeable indoor shaking. Unsecured objects may fall. Serious damage is uncommon. |
| Moderate | 5.0–5.9 | Damage to weak or unreinforced buildings. Chimneys, plaster, and windows can fail. |
| Strong | 6.0–6.9 | Damage in populated areas. Poorly built structures may collapse; well-built buildings can still be badly damaged close to the epicenter. |
| Major | 7.0–7.9 | Serious damage over a wide area. Many buildings unusable. Lifelines (power, water, roads) often disrupted. |
| Great | 8.0 or higher | Severe destruction near the fault. Damage can extend hundreds of miles. |