Resolution_2025 Kittitas County Hazard Mitigation Plan

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2025 Hazard Mitigation Plan Kittitas County, Washington Chapter 4: Hazard Identification and Risk Assessment 148 4.6.6.7. FEMA NRI Expected Annual Loss Estimates A landslide NRI EAL score, and rating represent a community's relative level of expected building and population loss each year due to landslides when compared to the rest of the United States. The EAL score is positively associated to a community’s risk; therefore, a higher EAL score results in a higher Risk Index score. Table 4-89 outlines the landslide EAL for Kittitas County. Table 4-89. Landslide Expected Annual Loss (FEMA National Risk Index) Jurisdiction Population Equivalence Building Value Agriculture Value Total Expected Annual Loss Expected Annual Loss Score Rating Kittitas County $61,729 $19,713 n/a $81,441 78.2 Relatively High Expected annual loss scores are calculated utilizing an equation that combines values for exposure, annualized frequency, and historic loss ratios (Expected Annual Loss = Exposure x Annualized Frequency x Historic Loss Ratio). 4.6.6.8. Landslide Risk Index Scores The FEMA landslide Risk Index score and rating represent a community's relative risk for landslide when compared to the rest of the United States. Table 4-90 illustrates the landslide Risk Index rating and score for Kittitas County. Table 4-90. Landslide Risk Index (FEMA National Risk Index) Jurisdiction Rating Score Kittitas County Relatively High 76.9 Risk Index scores are calculated using an equation that combines scores for Expected Annual Loss due to natural hazards, Soci al Vulnerability and Community Resilience (Expected Annual Loss x Social Vulnerability / Community Resilience = Risk Index). Table 4-91 represents the landslide Total Risk Score for the Kittitas County, based on the Risk Assessment Methodology, as defined in Section 4.3 of this Plan. Table 4-91. Landslide Total Risk Score Hazard Event Probability Consequence Total Risk Probability Factor Extent Vulnerability Impact Consequence Score Total Risk Score* Landslide 2 12 12 13 37 39 Consequence: Sum of all weighted factors. Extent: Sum of the weighted Extent factors. Vulnerability: Sum of the weighted Vulnerability factors. Impact: Sum of the weighted Impact factors. Total Risk Score = Probability x Consequence * Normalized to 100 Total Risk Score Legend Classification Probability Factor Extent Vulnerability Impact Consequence Score Total Risk Score Low (L) 1 0 – 6 0 – 6 0 – 12 0 – 24 0 – 24 Medium (M) 2 7 – 12 7 – 12 13 – 26 25 – 50 25 – 52 High (H) 3 13 – 18 13 – 18 27 – 39 51 – 75 53 and above The legend—specifically the assignment of low, medium, and high—provides an additional means to qualitatively assess the probability factor, sum of weighted factors, and the total risk scores for each hazard. The Consequence Score represents the sum of the Extent, Vulnerability, and Impact Factors. The Total Risk Score is a measure of Probability and Consequence.