What is disaster?

Disaster must be analyzed through the lenses of i) hazards, ii) vulnerability, and iii) risks.
Hazard is the process, the potential harm of an event.
Vulnerability is the degree of the impact of hazards on social processes and defined by i) poverty ii) political powerless iii) physical weaknesses and iv) isolation.
And disaster risk is a function of i) magnitude ii) potential occurrence iii) frequencies iv) speed of onset v) spatial extent vi) people’s susceptibility to loss, injury, and death.

DR = H x V
DR: Disaster Risk
H: Hazards
V: Vulnerability

Protective actions (C) is designed to counteract DR. The larger C is, the less DR becomes.
DR = H [ V/C – M ]
M: Mitigation by preventive action and social protection.

Ben Wisner, JC Gaillard, and Ilan Kelman. “Handbook of Hazard and Disaster Risk”. London: Routledge, 2011, in press.