Change is the law of nature. It is a continuous process that goes on uninterruptedly involving phenomena, big and small, material and nonmaterial that makes our physical and socio-cultural environment. It is a process present everywhere with variations in terms of magnitude, intensity and scale. Change can be a gradual or slow process like the evolution of landforms and organisms and it can be as sudden and swift as volcanic eruptions, tsunamis, earthquakes and lightning, etc. Similarly, it may remain confined to a smaller area occurring within a few seconds like hailstorms, tornadoes and dust storms, and it can also have global dimensions such as global warming and depletion of the ozone layer.

Besides these, changes have different meanings for different people. It depends upon the perspective one takes while trying to understand them. From the perspective of nature, changes are value-neutral (these are neither good nor bad). But from the human perspective, these are value-loaded. There are some changes that are desirable and good like the change of seasons, ripening of fruits, while there are others like earthquakes, floods and wars that are considered bad and undesirable.

In this chapter, we will read about some of these changes, which are considered bad and have haunted humankind for a long time.


Disaster, as defined by the United Nations, is a serious disruption of the functioning of a community or society, which involve widespread human, material, economic or environmental impacts that exceed the ability of the affected community or society to cope using its own resources.

What is a Disaster?

“Disaster is an undesirable occurrence resulting from forces that are largely outside human control, strikes quickly with little or no warning, which causes or threatens serious disruption of life and property including death and injury to a large number of people, and requires therefore, mobilisation of efforts in excess of that which are normally provided by statutory emergency services”.

The root of the word disaster ("bad star" in Greek) comes from an astrological sense of a calamity blamed on the position of planets.

Though often caused by nature, disasters can have human origins. A disaster occurs when a hazard impacts on vulnerable people. The combination of hazards, vulnerability and inability to reduce the potential negative consequences of risk results in disaster.

There has been a change in the perception of natural disasters and hazards.

  1. Firstly, the magnitude, intensity, frequency and damages caused by natural disasters have increased over the years.
  2. Secondly, there is a growing concern among people the world over to deal with the menace created by these so that the loss of human life and property can be minimised.
  3. And finally, significant changes have taken place in the pattern of natural disasters over the years.

Important Terms

  • Natural Hazards: The elements of circumstances in the Natural environment that have the potential to cause harm to people or property or both.
  • Natural disasters: These are relatively sudden and cause large scale, widespread death, loss of property and disturbance to social systems and life over which people have a little or no control.

Hazard verses Disaster

Hazards and disasters may sound like the same thing, but there is a vital difference.

  • Hazard: Any source of potential damage, harm or adverse health effects to life, health, property or the environment. It is a condition/event that has potential for causing injury/ loss of life or damage to property/environment.
  • Disaster: A devastating impact of a hazard that negatively affects life, health, property or the environment on a scale sufficient to require outside assistance.

So, hazards will be considered disasters once they affect humans, but if they occur in an unpopulated area, they will remain hazards.

Previously, hazards and disasters were seen as two closely associated and interrelated phenomena, i.e. areas prone to natural hazards, were more vulnerable to disasters. Hence, people avoided tampering with the delicate balance that existed in a given ecosystem. People avoided intensification of their activities in such areas and that is how disasters were less damaging.

Technological power has given large capacity to human intervention in nature. Consequently, now, human beings tend to intensify their activities into disaster prone areas increasing their vulnerability to disasters.

  • Risk: The combination of the probability of an event and its negative consequences.
  • Vulnerability: The characteristics and circumstances of a community, system or asset that make it susceptible to the damaging effects of a hazard.
  • Coping capacity: The ability of people, organizations and systems, using available skills and resources, to face and manage adverse conditions, emergencies or disasters.
  • Environmental impact assessment: Process by which the environmental consequences of a proposed project or programme are evaluated, undertaken as an integral part of planning and decision-making processes with a view to limiting or reducing the adverse impacts of the project or programme.

Classification of Disasters

For a long time, geographical literature viewed disasters as a consequence of natural forces; and human beings were treated as innocent and helpless victims in front of the mighty forces of nature. But natural forces are not the only causes of disasters. Disasters are also caused by some human activities.

Disasters are routinely divided into natural or human-made. There can be disasters where there is no single root cause. Such disasters are more common in developing countries. A specific disaster may spawn a secondary disaster that increases the impact. A classic example is an earthquake that causes a tsunami, resulting in coastal flooding. Some manufactured disasters have been ascribed to nature.

Natural disasters

A natural disaster is a natural process or phenomenon that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.

Various phenomena like earthquakes, landslides, volcanic eruptions, floods, hurricanes, tornadoes, blizzards, tsunamis, and cyclones are all natural disasters. The rapid growth of the world's population and its increased concentration often in hazardous environments has escalated both the frequency and severity of disasters. Developing countries suffer more or less chronically from natural disasters due to ineffective communication combined with insufficient budgetary allocation for disaster prevention and management.

Natural disasters can be classified under four categories:

Classification of Natural Disasters
Atmospheric Terrestrial Aquatic Biological
Tropical cyclone
Frost, Heat, wave
Cold Wave
Volcanic eruptions
Soil Erosion

Tidal Waves
Ocean Currents
Storm surge

Insect Infection
Viral Disease
Bacterial Disease
Parasitic Disease
Fungal Disease
Prion Disease
Plants and Animals as colonisers (Locusts, etc.)

Human-made disasters

Human-instigated disasters are the consequence of technological or human hazards.

Examples include stampedes, fires, transport accidents, industrial accidents, oil spills, nuclear explosions/nuclear radiation. War and deliberate attacks may also be put in this category. Other types of induced disasters include the more cosmic scenarios of catastrophic global warming, nuclear war, and bioterrorism.