Question

report on natural disasters .. about 300-350 words
tnx

Answer 1

Nature and Management:

A natural disaster is unforeseen, severe and immediate. Pollution, ozone depletion in the stratosphere and global warming come in this category. Natural disasters include cyclones, earthquakes, floods, drought (though these two are now being increasingly considered ‘man- made’ disasters) heat and cold waves, landslides, avalanches, flash floods, severe thunder­storms, hail, low level wind shears, and microburst.

Growing industrialisation and unjustified exploitation of natural resources have brought our echo system to a verge of non-reversibility and imbalance. This has led to a threat from a set of natural hazards like pollution, global warming and ozone depletion on large or global scale.

Management:

The management aspect of disaster may be classified as: (a) early warning system; (b) rescue operations; (c) relief operations; (d) rehabilitation; and (e) long range planning. The most important is the early warning systems. Unless sufficient advance notice is available, evacuation of the population likely to be affected cannot be undertaken.

There are two aspects of early warning system. One is the availability of an effective technique to forecast the disaster with its extent and the other is effective communication of the same to the civil authority responsible for rescue operations.

In some phenomena, such as cyclones, flood, etc. the time available to respond to the hazard is of the order of a few days. Hence early warning, communication, and rescue operations are possible. But, in a few cases like flash floods, microburst, etc., the response time is of the order of few minutes only, which calls for a very fast early warning and efficient communication system.

The human-activity-induced hazards like pollution and global warming have already started showing their precur­sors, giving sufficient time to control and avoid these hazards by long term planning. On the contrary, in earthquakes no proven methods has yet been evolved to give any prior warning and so post-hazard mitigation is the only alternative.

Role of Communication For a developing country like India, the role of communication in disaster mitigation is extremely critical. Vast areas of the country do not have telephone/ telegraph links. These can neither be provided in a short span of time available for mitigation nor are there resources to do so.

We have to depend on existing links, many of which completely break down during the disaster. The various types available for dissemination of disaster warning as well as arranging mitigation are: (a) land line links; (b) underground cable links; (c) wireless links; (d) microwave (LOS); and (e) satellite links. The only effective communication which is likely to remain completely or partially unaf­fected is the satellite link.

This assumes that the earth stations at the two ends are suitably located to remain unaffected. Further link between the earth station and the affected area is usually through microwave/ land line, which has its limitation as it may break down.

The most effective way of dissemination of warning is Disaster Warning System (DWS) used by the IMD for issue of cyclone bulletin to the coastal areas. This could be extended to the entire earthquake/ flood prone areas. Experience has shown that it remains completely unaffected under the severest cyclonic condition. However, the system is limited to one way communication only.

For effective two way communication, VHF/UHF links should be established from every earth station to the affected zone. Use of existing police VHF/UHF link can be made. The only addition required is the missing link between the nearest earth station to police headquarters. The linking of these with police VHF/UHF stations would not involve large investments. This would be a cost effective and reliable communication system for disaster warning and mitigation.

Earthquake:

Stated simply, ‘an earthquake is a vehement shake of the earth from natural causes’. Technically an earthquake is a phenomenon of strong vibrations occurring on the ground, consequent to release of large amount of energy within a short period of time because of some disturbance in the earth’s crust or in the upper part of the mantle.

Causes:

The theory of plate tectonics offers a comprehensive explanation for several geological phenomena — continental drift, mountain building and volcanism, and, of course, earthquake. According to this theory, when the molten mass that was the earth billions of years ago cooled down, the crust that was formed was not one homogenous piece but broken into about a dozen large plates and several smaller ones with their thickness ranging from 30 km down to the lithosphere at depth of about 100 km or so.

Answer 2

The earth’s weather is very mysterious. One day it is sunny the next it is raining. In fact, sometimes as you are driving down the road, you hit the “wall” between a sunny day and a sever thunderstorm. Man has spent years trying to predict weather patterns but it is still an inexact science. This is a list of the most common occurring disasters of nature:

1. Hurricane

Hurricanes, tropical cyclones, and typhoons are different names for the same phenomenon: a cyclonic storm system that forms over the oceans. It is caused by evaporated water that comes off of the ocean and becomes a storm. The Coriolis Effect causes the storms to spin, and a hurricane is declared when this spinning mass of storms attains a wind speed greater than 74 mph. Hurricane is used for these phenomena in the Atlantic and eastern Pacific Oceans, tropical cyclone in the Indian, and typhoon in the western Pacific.

2. Earthquake

An earthquake is the result of a sudden release of energy in the Earth’s crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph.Intensity of shaking is measured on the modified Mercalli scale. At the Earth’s surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground.

3. Tornado

Tornadoes are violent, rotating columns of air which can blow at speeds between 50 and 300 mph, and possibly higher. Tornadoes can occur one at a time, or can occur in large tornado outbreaks along squall lines or in other large areas of thunderstorm development. Waterspouts are tornadoes occurring over water in light rain conditions.

4. Volcanic eruption

A volcanic eruption is the point in which a volcano is active and releases lava and poisonous gasses in to the air. They range from daily small eruptions to extremely infrequent supervolcano eruptions (where the volcano expels at least 1,000 cubic kilometers of material.) Some eruptions form pyroclastic flows, which are high-temperature clouds of ash and steam that can travel down mountainsides at speeds exceeding that of an airliner.

5. Tsunami

A tsunami is a series of waves created when a body of water, such as an ocean, is rapidly displaced. Earthquakes, mass movements above or below water, volcanic eruptions and other underwater explosions, landslides, large meteorite impacts comet impacts and testing with nuclear weapons at sea all have the potential to generate a tsunami.