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Impact can be expressed as the relationship
between hazard effects and vulnerability. As the hazard grows in potential
magnitude and its potential effects increase equivalently, the overall
impact grows if vulnerability remains the same. If vulnerability also
increases the progression in impact may be geometrical. If positive measures
reduce vulnerability, impact may remain at the same level or even decreases
in spite of intensity increases.
It is important to note that we can characterize impacts as either hazard
specific or as functionality specific. For example, a hurricane has storm
surge, beach erosion, coastal flooding, inland flooding, and wind related
impacts. But we can also examine impacts as functional – electric power
utility outages may happen in hurricanes, earthquakes, winter ice storms,
urban fires, terrorism, etc. Understanding impacts both ways are important.
The hazard specific approach informs planning for specific events. The
functional approach is important to decreasing the vulnerabilities of
functions and systems. |