5. Learning Objectives
• To describe how hazard becomes a disaster
• To differentiate hazard, vulnerability, exposure,
disaster, and disaster risk
• To analyze the impacts of disasters
• To list ways to reduce the impact of disasters
7. The Occurrence of a Disaster
The occurrence of a disaster depends on the interplay
between a natural phenomenon or event (that can turn
into a hazard) and the vulnerability of populations
exposed (exposure and vulnerability).
8. When Does a Natural Event
Become a Hazard?
⮚ Natural events do not automatically become hazards,
much less cause disasters.
⮚ Under what circumstances then do natural
phenomena can be considered hazards?
9. When Does a Natural Event
Become a Hazard?
Natural phenomena can be considered hazards
when the threat of damage, injury, and even
death exists.
11. When Does a Hazard
Become a Disaster?
⮚ A disaster happens when the probable destructive
agent, known as the hazard, hits a vulnerable
populated area.
⮚ Therefore, a natural event like a volcanic eruption or
tsunami becomes a disaster only if it hits vulnerable
populations and properties.
14. Recognizing the Differences
of Disasters
No two disasters are alike. And although some are
definitely similar, appreciating their differences in terms
of their nature and magnitude of triggering hazards,
exposed elements at risk, and vulnerabilities will help us
deal with potential disasters.
15. Factors That Determine the Magnitude of
Disaster
1. The severity of the natural event
2. The quantity of exposure of the elements at risk which
includes lives and properties
3. Vulnerability level or quality of exposure
16. The Elements of Risk
⮚ Thus, Disaster Risk can be expressed as a function of
hazard, exposure, and vulnerability
or
Disaster Risk = Hazard x Exposure x Vulnerability
