2. Definitions and classifications

#### 2.1. Why we need to define and classify disasters?

We need to define and classify disasters to have better knowledge and understanding of the problem. This will enable concerned specialists and leaders to discuss the conditions and responses needed in more detail. The response may include shifting of resources and manpower or preparing alternative places to shift victims. Analysis of disasters shows that all disasters share common characteristics; they include temporal and geographic footprints, triggering hazard (or hazards), and vulnerabilities [5, 6].

Disaster: The word disaster is derived from Middle French désastre and that from Old Italian disastro, which in turn comes from the Ancient Greek pejorative prefix δυσ-, (dus-) "bad" and ἀστήρ (aster), "star." The root of the word disaster ("bad star" in Greek) comes from an astrological sense of a calamity blamed on the position of planets and ἀστήρ (aster), "star" [7].

The linguistic definition of the world disaster is "a sudden calamitous event bringing great damage, loss, or destruction" [8].

World Health Organization (WHO) definition of disaster: "A disaster is an occurrence disrupting the normal conditions of existence and causing a level of suffering that exceeds the capacity of adjustment of the affected community" [9].

United Nation Office for Disaster Risk Reduction (UNISDR) defines disasters as "A serious disruption of the functioning of a community or a society at any scale due to hazardous events interacting with conditions of exposure, vulnerability and capacity, leading to one or more of the following: human, material, economic and environmental losses and impacts" [10].

Federal Emergency Management Agency (FEMA) defines disaster as "An occurrence that has resulted in property damage, deaths, and/or injuries to a community. FEMA 1990" [11].

International Federation of Red Cross (IFRC) added another factor to the definition: "A disaster is a sudden, calamitous event that seriously disrupts the functioning of a community or society and causes human, material, and economic or environmental losses that exceed the community's or society's ability to cope using its own resources." Though often caused by nature, disasters can have human origins [11].
