SECTION 4: RISK ASSESSMENT
4.6
CONCLUSIONS ON HAZARD RISK
Priority Risk Index As discussed in Section 4.3 Risk Assessment Methodology and Assumptions, the Priority Risk Index was used to rate each hazard on a set of risk criteria and determine an overall standardized score for each hazard. The conclusions drawn from this process are summarized below. Table 4.100 summarizes the degree of risk assigned to each identified hazard using the PRI method. Table 4.100 – Summary of PRI Results
Spatial Extent
PRI Score
Hazard
Probability
Impact
Warning Time
Duration
Dam Failure
Possible
Critical Minor Minor Critical Critical
Negligible
Less than 6 hrs
Less than 1 week
2.4 2.5 1.9 3.3 2.8
Drought
Likely
Large Large Large Small
More than 24 hrs More than 1 week
Earthquake Extreme Heat
Unlikely
Less than 6 hrs
Less than 6 hrs
Highly Likely
More than 24 hrs Less than 1 week
Flood
Likely
6 to 12 hrs
Less than 1 week
Hurricane & Tropical Storm
Likely
Critical
Large
More than 24 hrs Less than 24 hrs
2.9
Landslide
Unlikely
Minor Minor
Negligible
6 to 12 hours
Less than 6 hrs
1.2 2.3
Severe Weather: Hail 1
Highly Likely
Small
6 to 12 hrs
Less than 6 hours
Severe Weather: Lightning 1
Highly Likely
Minor
Negligible
6 to 12 hrs
Less than 6 hours
2.1
Severe Weather: Thunderstorm Winds 1 Severe Winter Storm
Highly Likely
Limited
Large
6 to 12 hrs
Less than 6 hours
3.0
Highly Likely
Limited Critical Limited
Large Small
More than 24 hrs More than 1 week Less than 6 hrs Less than 6 hours
3.0 2.7 2.5
Tornado Wildfire
Likely
Possible
Moderate
Less than 6 hrs
Less than 1 week
Hazardous Materials Incident Radiological Emergency
Highly Likely
Minor
Negligible
Less than 6 hrs
Less than 24 hrs
2.3
Unlikely Unlikely
Catastrophic
Small
Less than 6 hrs More than 1 week
2.7 2.2
Terrorism
Catastrophic Negligible
Less than 6 hrs
Less than 6 hrs
1 Note: Severe Weather hazards average to a score of 2.5 and are therefore considered together as a high risk hazard.
The results from the PRI have been classified into three categories based on the assigned risk value which are summarized in Table 4.101: High Risk – Widespread potential impact. This ranking carries a high threat to the general population and/or built environment. The potential for damage is widespread. Medium Risk – Moderate potential impact. This ranking carries a moderate threat level to the general population and/or built environment. Here the potential damage is more isolated and less costly than a more widespread disaster. Low Risk – Minimal potential impact. The occurrence and potential cost of damage to life and property is negligible or nonexistent. This is not a priority hazard for mitigation projects.
Wake County Multi-Jurisdictional Hazard Mitigation Plan 2019
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