Disaster, whether natural or anthropogenic, are sudden and unfortunate extreme events of hazards which cause great damage to human beings as well as plants and animals. Disasters occur rapidly, instantaneously and indiscriminately. A hazard may become disaster only when it strikes the inhabited area. The following are the characteristics features of disasters:
- Disasters are natural or man-induced hazards.
- Disasters occur rapidly, instantaneously and indiscriminately.
- Disasters are always viewed in terms of damage to human beings i.e. serve damage to human life and property.
- Hazardous environmental processes always create extreme events but not all extreme events because disaster; they become disasters when they occur in the inhabited area and adversely affected the human society.
- Disasters create socio-economic and health problems.
Classification of Hazards and Disasters
Environmental hazards and disasters may be classified under the following categories:
- Natural hazards
A. Natural Hazards and Disasters
- Volcanic disasters
- Seismic disasters
B. Atmospheric Disasters
- tropical cyclonic disasters
- hailstorm disasters
- lightning disaster
- heat waves and cold waves
- soil erosion
- Reservoir-induced seismic disaster
- man induced landslides
- chemical disasters
- nuclear disasters
- Failure of nuclear plants
- nuclear wars
Natural disasters are caused by the endogenetic and exogenetic forces. The natural disasters may be sudden or slow processes. Scientific prediction about the sudden disasters like earthquakes is not possible. All earthquakes, however, are not disasters. For example, if an earthquake of 7 or 8 magnitude on Richter Scale occurs in a desert or uninhabited areas it is not a disaster, but if an earthquake of only 5 magnitudes occur in a populated, there may be enough damage to life and property it may be a hazard or disaster.
According to the report of the United Nations Disaster Relief Coordinator (UNDRC) nearly 90 per cent of all the reported natural hazards and disasters occur in the developing countries. Out of the natural disasters, earthquakes are the cause of most deaths and loss of property. It may be observed from Table 1 that earthquakes dominated over the other natural disasters. Between 1970 and 2011.
The damage by a disasters can be reduced by adopting the following:
1.Pre-disaster stage (anticipatory stage or preparedness stage)
2.On disaster stage (participatory stage or mitigation stage)
3.Post-disaster stage (post disaster stage or recovery stage)
1.Pre-disaster Stage or Preparedness: Preparedness means the necessary arrangements to meet any eventuality if a hazard strikes a locality or community. It includes the demarcation of vulnerable areas of hazard, preparation of vulnerability map, risk assessment prediction technique, disaster warning system. It also include the education of masses about the avoidance of hazards and taking safety measures in the event of occurrence of a disaster.
2.Disaster Mitigation or Participatory Stage: The disaster mitigation stage focuses on to reduce the adverse impact of the disaster. It requires proper land use planning, protection of mangroves, improvement design and structure of buildings, the participation of the local community, participation of government agencies and non-governmental organizations (NGOs), international agencies (Red Cross, Crescent Societies, World Health Organisation, etc.).
3. Post Disaster Stage ( Recovery Stage): The post-disaster stage includes (i) relief measure, recovery from shocks of disasters, and rehabilitation of displaced people. Disaster recovery is a community-based process. Community participation is a prerequisite condition to recover the individuals and community from the agony of the trauma of disasters.
Volcanic Disaster Reduction
Volcanic eruptions cannot be avoided but the loss to life and property can be reduced substantially by making a timely prediction. The management and reduction of volcanic disaster involve the two measures given below:
(i)Prediction and early warning of the eruption. There are certain precursorevents which help in the prediction of eruptions of dormant volcanoes. These events include (i) increase in the frequency of tremors, (ii) rise in the temperature of the crater lake, (iii) deformation of existing craters, (iv) emission of gases and smoke from existing crater, and (v) restlessness among birds and animals.
(ii)Timely evacuation and relief work.
Earthquake is a sharp release of energy that produces in Earth’s crust at the moment of rupture along a fault or in association with volcanic activity. A scientific prediction about the earthquakes is not possible till date. Some of the steps which can reduce the loss of life and property are given below:
1. Delineation of earthquake zones.
2. Prohibition in the construction of houses, hotels, settlements, and industries in the seismic zones of high vulnerability.
3. Construction of earthquake-resistant buildings and structures.
4. Use of superior quality of building material.
5. Avoid the construction of large dams and reservoirs in high seismic zones.
6. Earthquake disaster preparedness
7. Efficient search and rescue operation
8. Prompt relief operation after occurrence of earthquake.
9. Recovery of disaster-affected people from mental, economic and social problems.
10. Rehabilitation of the displaced people.
Tsunami Disaster: Tsunami is a seismic sea wave, travelling at high speeds across the ocean, formed by sudden and sharp motions in the seafloor, such as sea-floor earthquakes, submarine landslides, or eruptions from undersea volcanoes. The occurrence of tsunami causes heavy loss to life and property including livestock, crops, fishing, tourism, transport system. Destruction of sea beaches, deposition of sand on coastal plains, destruction of marine resources including corals and fishes.
Management of Tsunami Disaster: The loss of life and property occur from tsunami may be reduced substantially by adopting the following steps:
1.Pre-tsunami Disaster Stage: Identification and mapping of areas of tsunami-vulnerable areas. The coastal zone regulation should be strictly enforced in order to save people from the tsunami waves. In India Coastal Regulation Zones were declared through government notification in 1991.
2.Demarcation of coastal regulation zone (CRZ) and to make it free from human settlements.
3. Protection and conservation of mangroves and other vegetation along the coastal areas, especially the areas vulnerable to tsunamis.
4. Installation of tsunami prediction devices along the coasts.
5. Provision of early tsunami warning system and efficient evacuation of people living in the tsunami vulnerable coastal areas. The Pacific Tsunami Warning System (PTWS) was set up in 1948 with total membership of 26 countries around the Pacific.
Post –tsunami Disaster Stage: In case tsunami struck, the following steps should be taken to minimize the damage to life and property and to provide relief to the affected people.
1. Rescue and evacuation of the stranded alive people.
2.Immediate medical relief to the injured people.
3.Immediate relief and provisions of food and drinking water.
4. Rehabilitation of the displaced and affected people.
5. Avoid disaster area. Your presence may hamper rescue and other emergency operations.
6. help people who require special assistance, e.g. infants, elderly people, disables, females and injured.
7. Stay out of building if water remains around it. Tsunami water can weaken the foundation, causing building to sink, floors to crack, or walls to collapse.
8.When entering buildings or homes, be very careful. Carefully watch every step you take.
9.Use battery –powered lantern of flashlights when examining buildings. Battery powered lighting is the safest and easiest to use does nota fire hazard for the user. Do not use candle or lighter. Check for gas leak.
10. watch out for wild animals, especially poisonous snakes that may have come into building with the water.
11. Rehabilitation of the affected people.
Landslide: Landslide is a general term for relatively types of mass movement, such as debris flow, debris slides, rockslides, and slumps. Gravity is the driving force for the down-slope movement of material. Like other natural hazards, the mitigation landslide disaster involves two stages of action, namely (i) pre-disaster stage, and (2) post-disaster-stage.
1. The landslide prone areas should be surveyed and plotted on large scale maps.
2. There should be prohibition in the construction of human settlements and building activities. in the landslide prone areas.
3. In the construction of roads and National Highways, the principles of ecology should be followed strictly.
4. Deforestation and over grazing on vulnerable slopes should be prohibited.
5. Massive reforestation on the denuded and deforested slopes.
6. In the post-landslide disaster there should be the immediate rescue of stranded alive people buried under debris.
7. People from the affected area should be removed to safer areas for their rehabilitation.
Management of Tropical Cyclonic Disaster
Tropical cyclone is a cyclonic circulation originating in the tropics, with wind between 39 to 73 miles per hour, characterized by closed isobars, circular organization and heavy rains. Tropical cyclones are natural phenomena and they result from the atmospheric oceanic dynamics and hence their occurrence can not be prevented. The reduction in loss of life and property and management include the following steps: (i) Preparedness, (ii) Mitigation, (iii) Prevention, (iv) Relief work, (v) Recovery, and (vi) Rehabilitation. The following steps can go a long way in reducing the loss to life and property.
(i). Detection of cyclone, (ii) Identifying the position of a cyclone, (iii) magnitude and dimension of the cyclone, Forecasting, communication and warning. There should be efficient forecasting system of cyclones like that of USA and Japan. The cyclone prediction in the developing countries is however not efficient.
Tornado: Tornado is an intense, destructive cyclonic rotation, developed in response to extremely low pressure, associated with meso-cyclone formation. Tornadoes are very violent rotating system of air wherein the air from the ground surface having lowest pressure is sucked by the upper air and is suddenly uplifted causing convective instability. The diameter of upper funnel increases from 90 m in the lower portion say at the ground to 460 m in the upper portion say at the top.
The unpredictability and ferocity of tornadoes make protection and preparedness very difficult. The average number of annual deaths due to tornadoes is decreasing. Recently, Doppler radars are used in the study of different aspects of tornadoes, their prediction and warning. The Doppler radar also determine the speed and direction of tornadoes. Installation such devices can help can reduce the risk of tornadoes.
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