Generally a disaster evolves in phases, as under. Out of these, the reconstruction and rehabilitation phase lasts the longest, depending on the resources of the community and administrative authorities.
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1. Predisaster phase
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2. Impact phase
3. Post impact phase
4. Reconstruction and rehabilitation phase.
1. Predisaster Phase:
Before a disaster strikes a community has to assess risks, train the people to be prepared, and plan programmes to avert a disaster, if possible. It can do this itself but external help is very desirable.
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Risk assessment: The aim is to make people both aware of the nature of particular local risks and ready to respond promptly in their area. It is meant to demonstrate those risk factors that need to be addressed in order to mitigate the effects of the disaster.
Sudden onset disasters assessment must consider both the risk factors which increase deaths; and the resources necessary for relief.
The local hospital will have an active role to play both before and after a disaster, because a good state of preparedness may reduce the impact of the disaster, the greatest number of lives can be saved, and many problems of the survival health can be dealt with more efficiently if the hospital is active and well-organised.
Training: Training for preparedness is the key to successfully deal with disasters. The aim of training in the predisaster phase is to develop the skills listed below:-
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i. Effective personal protection from falling debris.
ii. Prompt rescue of the wounded
iii. Triage of the wounded
iv. Resuscitation and first aid for injured victims
v. Prepositioning of relief supplies needed for the post- impact phase such as surgical equipment, essential medicines, blankets, tents
vi. Establishment of temporary water supplies
vii. Allocation of responsibilities for different relief activities to avoid unnecessary chaos.
2. Alert Phase:
The alert phase refers to the period when a disaster is developing. The duration of the alert phase varies according to the type of disaster, for example, it is nonexistent for earthquakes, short but crucial in case of hurricanes, and quite long in case of draught and famine.
3. Impact Phase:
The needs of the community during this phase depend largely on the characteristics of the disaster and the degree of preparedness.
Earthquakes, for example, are unpredictable, sudden and highly lethal. By contrast, hurricanes and cyclones are usually more predictable.
Most deaths in earthquakes are due to crushing injuries, occur immediately or soon after the impact. Additional deaths are due to burns from fires which sometime break out soon after.
In earthquakes there is a high level of mortality as a result of people being crushed by falling objects.
Earthquakes at night are more deadly. During the night fractures of pelvis, thorax and spine are common because people are lying in bed. In the daytime, injuries to the arms and legs, collarbone and skull frequently occur.
The priorities of a relief effort after an acute natural disaster should reflect these realities. The immediate response should not await a detailed assessment of impact.
The effectiveness of the relief effort will depend entirely on local efforts, on how adequately the community is prepared.
During this phase, planning will include activation of the response mechanism, daily monitoring; updating of response measures, if necessary; and coordinating outside assistance.
4. Post impact Phase:
This phase may vary between a few days and several months following the initial impact.
The following actions will be required during this phase:
i. Evacuating the survivors to safe areas and provide shelters to the homeless
ii. Providing food and water
iii. Continuing the triage and transportation of the injured to appropriate facilities.
iv. Re-establishing primary health care services
v. Re-establishing sanitary measures to prevent outbreak of epidemics.
The destruction of sanitary and sewage facilities due to disaster leads to indiscreet disposal of liquid and solid waste and excreta, creating insanitary conditions adding to the problem.
Health implications in these situations usually manifest in the form of food and water-borne disease.
The effect on health facilities and health manpower, which are also affected by a disaster, greatly hamper the immediate mobilisation of medical and public health services.