History and Impact of Natural Hazards & Disasters

Disasters are as old as human history but the dramatic increase and the damage caused by them in the recent past have become a cause of national and international concern. 

A Disaster is a serious disruption of the functioning of a community or a society involving widespread human, material, economic or environmental losses and impacts, which exceed the ability of the affected community or society to cope using its own resources. 

Disasters can be caused by naturally occurring events, such as earthquakes, hurricanes, flooding, or tornadoes, or they can be due to man-made events, either accidental (such as an accidental toxic spill or nuclear power plant event), or deliberately caused (such as various terrorist bombings and poisonings).

Meaning of Disaster: Elements, Impact, and Global Trends

• Definition: It can be defined as “A serious disruption in the functioning of the community or a society causing widespread material, economic, social or environmental losses which exceed the ability of the affected society to cope using its own resources”.

• The Interplay of Elements: It is a result of the combination of Natural Hazards, vulnerability and insufficient capacity  to reduce the potential chances of risk (Refer Figure)

Meeting of Vulnerability and Hazard Causing Disaster

• The Lethal Impact: Drought and famine have proved to be the deadliest disasters globally, followed by floods, technological disasters, earthquakes, wind storms, extreme temperature, etc. 
  • Global economic loss related to disaster events averages around US $880 billion per year. Figure shows the deadliest disasters of the decade (1992 – 2001).

Danger Defined: Manmade and Natural Hazards

• Definition: Natural Hazards may be defined as “a dangerous condition or event that threatens or has the potential for causing injury to life or damage to property or the environment’’.
• Classification: Hazards can be grouped into two broad categories namely natural and manmade:
  • Natural hazards:
    • These hazards have natural origin such as meteorological, geological or even biological origin.
    • Geological origins such as cyclones, tsunamis, earthquakes, volcanoes etc.
    • Biological origins such as viral, fungal etc.

• Manmade hazards: These occur due to human negligence and are associated with industries or energy generation facilities and include explosions, leakage of toxic waste, pollution, dam failure, wars etc.

Vulnerability: Physical and Socio-economic Aspects

• Definition: Vulnerability may be defined as “the extent to which a community, structure, services or geographic area is likely to be damaged or disrupted by the impact of a particular hazard, on account of their nature, construction and proximity to hazardous terrains or disaster-prone area”.

• Classification: Vulnerabilities  can be categorised into physical and socio-economic vulnerability. 
  • Physical Vulnerability: Impact of Natural Hazards on Structures
    • It includes notions of who and what may be damaged or destroyed by natural hazards. 
    • It is based on the physical condition of people and elements at risk, such as buildings, infrastructure etc.

• • Socio-Economic Vulnerability:   Disparities in Natural Hazards & Disaster Vulnerability
    • It refers to the degree to which individuals and communities are susceptible to harm from disasters due to their social and economic status.
    • Example: People who are poor and living on the sea coast are generally at higher risk vis-a-vis rich people in case of cyclones and floods.

Risk: Assessing Natural Hazards and Losses

• Meaning: Risk is a measure of the expected losses due to a hazard event occurring in a given area over a specific time period.
• Risk Assessment and Loss Estimation: 
  • It is a function of the probability of a particular hazardous event and the losses each would cause. 
  • A community is said to be at ‘risk’ when it is exposed to hazards and is likely to be adversely affected by its impact.

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