An earthquake with its terrible aftereffects is one of the most frightening and destructive phenomena of nature. It can be defined as a sudden movement of the earth caused by sudden release of energy and strain that has been accumulated for a long time. For millions of years. The forces of tectonic plates mould the huge plates that make the earth's surface move slowly over, under and past each other. Sometimes the movement is gradual but at the other times the plates get locked together disabling themselves to release the accumulating energy. As this energy is very powerful, the plates break free which gives rise to an earthquake that may cause a great loss of life and property.
Sometimes due to earthquakes, volcanic eruptions or landslides large quantity of water is displaced which cause large and powerful waves. These are known as tsunamis. Explosion of nuclear devices under water can also cause tsunamis. As soon as these waves move into shallower water, they get high000er and higher having potential for causing major destruction when they reach coastal area.
A cyclone is a storm which is accompanied by high speed whistling and howling winds. Cyclonic storms generally generate over Tropical Ocean like the Indian Ocean, the Arabian Sea and the Bay of Bengal, bringing heavy rains together. The strong winds blow at a great speed, sometimes exceeding 118 kilometers per hour. As a cyclonic storm approaches, there appear dark clouds together with thunder, lightening and rain. They bring heavy floods. Electricity and telecommunication connection are paralysed resulting in power breakdown and communication failure. Road and rail transportation along with air services are severely disrupted.
A great number of trees are bent down or uprooted. House collapse and people are left homeless. The loose metal and wooden sheets over the kachha house. Especially in villages, fly becoming potential killers. The flood water takes time to come down. The land becomes salty, affecting the agriculture adversely. Infrastructure like bridges, dams face substantial damages. A potential danger or outbreak of epidemics like cholera, jaundice and viral diseases is always there due to impure water. Dead bodies of human beings and animals mixed with sewage contaminate water to a dangerous level.
Water is one of the most important natural resource but sometimes, its larger quantity can be proved disastrous too. In the form of flood it can destroy property and kill humans. It is a natural disaster when there is excess water in river, lake or even the ground can handle. When flood water rises suddenly and rapidly after heavy rainfall due to a thunder storm than it is known as flash flood. Nothing is enough to stop flooding; we can only minimize the losses resulting from the flooding of water. The best way to avoid damage is to abstain from building structures in the vicinity of areas prone to floods.
When there is lack of supply of moisture on account of less than normal rainfall, erratic rainfall distribution creating greater need of water then it is known as drought.
A number of definitions have derived for drought on the drought on the basic of various social and economic segments affected by them. Generally a drought has different meaning for different people. For a meteorologist it is the absence of rain but for an agriculturist it is the deficiency of moisture in the soil for supporting the growth and productivity of crops. For a hydrologist it is the low levels of water in various reservoirs but for the city management it means the scarcity of drinking water. Therefore, it is impossible to give a universal definition of drought.
Much has been done in the field of agriculture technology providing improved varieties of crops and better agricultural practices but still in our country, agricultural productivity greatly depends upon the monsoon. Acute shortages of water due to scarcity of rain over an extended period of time results into widespread failure of crops, acute shortage of drinking water, scarcity of fodder and hence take a form of horrifying drought.
The sliding or falling of rocks along with soil, dirt and other materials is known as landslide. They are geological hazard and can take place anywhere at any time. A great deal of damage is caused by landslides, especially when they are large.
Landslides can be caused due to earthquakes, de-stabilization of underground water, or the collapse of overhanging rocks. Some human activities like heavy construction, mining, and stripping ground cover like plants and trees can also trigger landslides. If a landslide involves mud or any wet material, then it is known as mud slide.