Severity of Consequence

Creating a universal understanding of hazard risk for the R2C AOI required a robust accounting of consequences from historical losses as well as the ability to project future scenarios.  Here, Severity of Consequences not only included historical losses, but also possible climate sensitivities, current high priority hazards, and those likely to cause continued losses if not mitigated. Consequently, this assessment calculates Severity of Consequences (Equation 6: Severity of Consequences Calculation) using equal parts Historical Consequence, Climate Sensitivity, a measure of probability versus consequence, and a measure of future impacts (or high priority hazards for the R2C AOI) derived from the current Hazard Mitigation Plans from AOI counties.

Historical consequences

A hazard’s historical consequence score is the sum of historical frequency, economic impacts, fatalities, and injuries from past disaster events (as outlined below).

Historical Consequence Calculation:

HISTCON (Haz) =Historical Frequency Score+Historical Economic Impacts Score+ @Historical Fatality Score+Historical Injury Score 

Where:

• Historical Frequency Score: A Min/Max standardized (1-5) indicator of recorded[1] frequency of occurrence for past loss causing Hazard (HAZ) events.

• Historical Economic Impacts Score: A Min/Max standardized (1-5) indicator of recorded damages from past loss causing Hazard (HAZ) events.

• Historical Fatality Score: A Min/Max standardized (1-5) indicator of recorded fatalities from past loss causing Hazard (HAZ) events.

• Historical Injury Score: A Min/Max standardized (1-5) indicator of recorded injuries from past loss causing Hazard (HAZ) events.

[1] https://www.ncdc.noaa.gov/stormevents/

Frequency/Severity

Generally, hazards fall into two specific types in terms of their frequency vs. their severity. Low probability/high consequence disasters (earthquakes, hurricanes) generally occur less frequently and have a much higher consequence when they do occur. Conversely, high probability/low consequence events (lightning, heat, hail) occur more often but cause less damage and impact on society. Each hazard event type was appraised on its frequency/severity by dividing the total loss by the total number of events and then standardizing/normalizing the resulting values on a (1-5) scale where 1 indicates hazard threats with less loss per hazard incidence and 5 indicates hazard threats with more loss per hazard incidence

Frequency/Severity and Priority for each county can be seen in the Composite Severity of Consequences section below.

Current priority

Each hazard included in the assessment has either impacted the R2C AOI in the past or has the potential to cause future impacts. Previous county hazard mitigation plans have prioritized hazards for mitigation funding and planning based on their own assessment of each hazard. Including individual county prioritization of hazards provides a connection between this plan and previous planning efforts and moves these assessments towards becoming living documents that have impact/influence on the current assessment.  Like the historical score, climate sensitivity, and severity/frequency scores, the hazard priority score ranges from low to high (1-5) for each hazard threat.

Frequency/Severity and Priority for each county can be seen in the Composite Severity of Consequences section below.

cOMPOSITE SEVERITY OF CONSEQUENCES

Combining historical consequences, climate sensitivity, probability/consequence, and future consequences results in a standardized value for the severity of consequences (SOC) for each hazard analyzed in this assessment. In this case, hurricane winds and storm surges, and flooding hazards poses the highest overall severity of consequences across most counties assessed.  However, because each SOC score is built from county specific information, the scores vary from county to county across the R2C AOI.  Each county’s SOC scores are sorted alphabetically.