Write short note on Strategies for conservation of wildlife

Strategies for Conservation of Wildlife : The conservation of living organisms is concerned with plants, animals and microbes of the biosphere in such a way that it would give great benefit to the present as well as future generations of man without reducing the potential. It takes into consideration the following objectives:

(i) Maintenance of ecological equilibrium between biotic and abiotic components.

(ii) Ensuring the optimum utilization of the existing plants and animals minimizing chance of their disappearance during the course of time.
(iii) Preservation of the total gene pools of the different species in the world.

It would be appropriate to mention some of the important steps proposed by various agencies of the world to save the existing wildlife.

(i) Wile life sanctuaries and national parks should be made keeping in mind the feeding, breeding and environmental needs of species concerned.

(ii) Proper planning of land and water utilization should be done to ensure the protection of wild life in their natural habitats such as zoo and botanic gardens.

(iii) Special attention should be given to conserve the species which fall in the category of endangered, vulnerable or rare species.

(iv) Attempts should be made at national level to identify natural habitats for specific wild animals and plants.

(v) The ecosystems having endangered or vulnerable species should be given priority with regard to their protection. The use of only such species or individuals should be allowed which will not disturb the balance in the ecosystem.

(vi) The protection of wild relatives of our food crops, forage plants and domesticated animals should be given priority because they are needed for introduction of desirable characters during the breeding programmes at national and international levels.

(vii) In the introduction of species between two countries, bilateral agreements should be reached to establish required network depending upon the need of the species.

(viii) Alternative measures should be adopted to allow the survival of a species being exploited by a country or a community or an industry.

(ix) The genetic diversity of a species should be safeguarded keeping in mind the international protection progammes, e.g., MAB (Man and Biosphere) project of UNESCO, and setting up of national parks and protected areas as suggested by JUCN.

What are the main causes of wild life depletion? 

Causes of wild Life Depletion : During the recent past, there has been a sudden decline in the number of wild animals. The hunting leopard or Cheetah is now extinct. The one horned Rhinoceros has survived because of the protective steps taken by the Government. The sanctuary of Givr forest has saved the lions from extinction. The great Indian Bustard is now facing extinction. Many ducks have become extinct in recent years.

1. Habitat Alterations:
(a) Absence of cover or shelter: The forest vegetation, tall grasses, margins of rivers, uneven ground etc. are used as cover of shelter by the wild animals. For example, the tall grass in the Kaziranga Sanctuary are used as cover by the Rhinos. Once cover is absent animals will not survive even if food and water are available in plenty.
(b) Pollution : The rivers and streams that run through the forests and plains contain untreated effluents of many factories which make the river waters unsafe for drinking and may even act as killing agents. Drinking. polluted water exposes them to disease and predation.
(c) Reduction in the area of Movement:  The forest area is being increasingly converted into cultivable lands. This reduces the freedom of movement of the wild animals to a large extent. Animals like deer, bison, tiger, rhino etc. are unable to maintain their numbers when confined to relatively small areas. This is one of the reasons why the wild animals in the zoo rarely reproduce.
(d) Destruction of wild plants : In order to get more timber, charcoal and firewood man has cut and destroyed many wild plants which form the main food of these animals Food is one of the major factors of the habitat which controls distribution and numbers of wild animals. The absence of the chief food may even end in ultimate depletion and extinction of some wild animals.
(e) Building roads and railways : For the improvement of our transport system a net work of roads and railways are built up. Most of the road and railway routes pass through the dense forests. This delimits the area of movement for the animals. Moreover, the timid animals shun away from the noise of passing vehicles.

2. Nature of Man : In the words of the Late pandit Nehru “In spite of our culture and civilization man continues to be wild but more dangerous than any of the so called wild animals.” Even rules and regulation may not help if people don’t improve in their attitude. The ignorance of the common man regarding the value of our wild life and the consequential indifference to what happens to them disappear. The day must come when man must feel that it is more exciting to shoot with a camera than with a gun.

3. Hunting:
(a) Hunting for pleasure : Among the rich people of India it was and is still a pastime to go hunting for pleasure. With the improvement of the nature of fire arms today and with modern aids like jeeps, binoculars and flash lights the number of animals shot for pleasure seems to be increasing beyond leaps and bounds.
(b) Bad hunting methods : Some primitive tribes use poison as a method for hunting. This results in the death of may animals. Other bad methods of hunting include setting fire to forest areas to drive away animals in one direction for being shot.
(c) Hunting for money : In a poor country like India there is always a great clamour for quick easy money. Hunting offers good prospects in this regard. The prices of animal products are always spiraling. A good tiger skin is worth three to five thousands rupees. Similarly, the tusks of elephants, and the skins of other big cats are also costly. The horns of rhinoceros carry fancy price. This has lead to the unlimited slaugher of these animals. Many big snakes are now reduced in number due to the export of snake skins. The meat of many animals like deer, will boar and Nilgai has always been in great demand and attracting many professional hunters.

4. Legal Lapse : The protection of wild life is a state subject and many state governments are unable to protect the wild life by suitable laws. The existing laws are inadequate and there is lack of enforcement of the
protective laws.

Explain the management of forest?

To encourage forestation and prevent wasteful approach of human beings, introduction of proper management methods is necessary. This would check block cutting, deforestation, pest and fire control. A recycling procedure ensuring continuous supply of forest products should be planned on long- term basis, so that the forest resources could last for a larger period. It is very important for our very, survival. For example, we need the modest- timber supply annually and this harvested crops should be replaced by an equal amount of timber crop growth. Timber trees grow mature in 15 to 100 years, so its recycling should be planned accordingly.

(1) Block cutting method is generally adopted in the forest which have even aged trees, of a few species only. Coniferous forests are cut in this way. Thus a particular area is denoted by cutting down its entire tree population. Such area may be in the centre of interior of the forest and the last forest area is replaced by reforestation of adjacent area of the same size. This would result in a sustained supply of forest products without adversely affecting the actual size of the forest. Thus the annual forest cutting is followed by annual replantation of the deforested areas. Deforestation should take place in a limited area only. Thus the forests would be conserved and its yield should be high. It would last for a very long period.

(2) By effective forest management, floods, soil erosion end expansion of desert can be checked. Floods in our country, to. a large extent is a result of indiscriminate and excessive deforestation every year. Moreover there are no effective measures to force replantation of trees in denuded area. Illegal falling of in nature trees add more problems. It is to be checked immediately.

(3) Forest and wild life conservation are intra-related as the forests serve as the best habitat for them The forests serve natural home for game animals. But due to deforestation and hunting, tiger and lions alongwith others, have undergone extinction.

(4) Parasitic fingi such as rusts, smuts and mildews, viruses and insects are some of the disease causing agents in the forest. Biological controls can be introduced. The insects bug feeds upon the weed Lantana and thus it can control its growth. Thus in such control, the biological agent is introduced to remove the undesirable species from an area. Some of the fungal viral resistant species of the forest trees have been produced and introduced in the forests.

(5) Timber is an important product of forest tress which is of high economical value. After removing the stem of timber trees, which are main source of timber, stumps, leaves, barks are left behind as waste.

A proper management of timber forests can only ensure this. This needs further plantation of forests in such a way that is double to deforestation, improved timber quality through genetic research, avoidance of useful cutting, control of forest, introduction of pests resistant varieties of trees and a planned, falling of trees.

Explain the Land and Water Management in India. Discuss Waste Land Development. 

India is a predominantly agricultural country. A large number of our industries also depend on agriculture. A survey of the present status of land in India has shown that most of our croplands, woodlands and grasslands have already become deteriorated owing to faulty agricultural practices. Soil erosion, deforestation, water logging, salination and urban encroachment have considerably affected our productive lands.
Out of India’s total land mass of 305 million hectares (ha) nearly half is considered as waste land. Around 18 million he are under urban and productive use. Another 21 million ha are rocky or snow-bound. Of the remaining 266 million are culturable waste, 23 million hectares are fallows, 83 million ha are classified as forests and pasture land and 143 million hectares are agricultural land.

The man-land ratio is very low in India. Due to high population pressure the per capita available land in our country is only 0.48 hectare. We must learn to survive with this serious limitation. This requires understanding, planning and integrated management of land and water.

The Himalaya is one of the most crucial watersheds in the world with very high sedimentation rate. Execution of environmentally unsound
developmental plans and defective land use in the mountains have created
grave problems in the plains of India, Bangladesh and Pakistan. Every year over 400 million people are ravaged by recurring floods and their consequences. With increasing misuse of the Himalayan slopes, damage to reservoirs and irrigation system is accelerating.

The treatment of catchments should be done on an environmentally sound basis. It must begin from the top-most reaches of the catchment. The land to be conserved should be planted with economically and socially useful trees and grasses, chosen according to edaphic and climatic conditions and local needs.

The productivity to canal irrigated lands in India is still very poor in comparison with that in other countries because of water — logging and salinity. Proper drainage and desalination practices can overcome these problems.

One untapped source of water in India is the ground water. There are several advantages in using ground water, These are:
(i) It can be tapped in a very short time.
(ii) The cost of tube-wells is low.
(lii) It is easier to raise the interest Of the farmers.
(iv) Irrigation is highly economical because it does not involve storage and transport.
(v) It is not vulnerable to evaporation and seepage losses.
(vi) The ground water is especially suitable in canal command areas because it helps in lowering the water tables and
(vii) A large amount of ground water is available even in dçsert areas.
A scientific investigation of the ground water potential together with the replenishment rates should be undertaken.

Wasteland Development

To meet the needs of the increasing population, the demand on land for agriculture, industry and settlement is increasing. On the other hand good land is shrinking due to degradation. As explained above, a large part of our country’s land is considered as wasteland. Wastelands can be broadly classified into two types : culturable wastelands (ravenous and gullied lands. Surface water-logged land and march, saline lands and lands with lateritic soils, shifting cultivation areas, degraded, forest lands, strip lands, mining and industrial wastelands, etc.) and unculturable wastelands (barren rocky areas, steep slopes, snow-capped mountains and glaciers). Development and reclamation of culturable wastelands can increase the availability of land for productivity.

Reclaimation of wasteland involves high expenditure, expertise and manpower. But wasteland that is reclaimable within the financial means and known techniques should be immediately undertaken. There are over 87 million hectare (ha) of agricultural land prone to degradation by severe erosion. This land must be saved on a priority basis measures that will minimize soil erosion. Some of these practices are creation of shelter belts, revegetation of steep slopes etc.

Explain any one problem produced due to urbanization.

Health problem produced due to urbanization

Various type of pollution in the cities have become a world wide problem which has put the human health in danger Despite a rapid progress in medical science the number and the types of diseases have increased in developing countries. In urban areas the overcrowding and noise cause various type of mental and physical diseases. In most of the developing countries it is difficult to provide the town planning and format. With the populations movements towards the urban areas, the diseases like Trachoma, Tuberculosis, parasitosis, Skin diseases are imported. The inflow of people in the urban areas carries along with them. The water affluent and waste disposal problems which cause various diseases in society also act as urbanized pressure.

The poor ventilation in houses, the use of cow dung in food cooking, accumulation of inorganic material etc. cause the rural pollution but the significance of biowaste in making the fertilizers is understood by rural people and many of such tasks are performed by them by naked hands. The absence of proper cleanliness leads to increased population of mosquitoes and flies which are the vectors of various diseases. The growth of the population produces grave problem of habitat and the facilities are associated with it. Except few sky scrappers and new colonies a big part of the population of India is inhabiting in unhealthy situation. In rural areas the positions of huts made up of soil and their living conditions are very poor and are said to be highly dis-satisfactory. Continued increases in population not only produces the present day problems but also presents the acute problems of the future.

Presently the population is increasing with a rapid rate. Its main reason in mainly the low death rate (mortality) and an increase in average span due to better medical facilities, cleanliness and increased facilities for public

Unplanned industrialisation has far-reaching consequences on ecological balance. For agriculture, it is required to clear forests for land. Also for establishing settlements and factories land is cleared. These settlements and factories may cause pollution if they are not planned properly in terms of space and civic amenities like water and sanitation.

The waste of the factory may get mixed with the water of the local water bodies which would contaminate the water and make it unfit for consumption. The smoke and gases coming out of the chimneys would pollute the air, leading to respiratory disease. Unplanned industrialization would also lead to vehicular traffic, leading to air and noise pollution and overuse of ground water which would result in falling of the water table.

Write short note on Environment and Sustainable Development.

Environment and Sustainable Development

Ancient man was living in jungles and was leading a harmonious life with the nature. But the modern man is living in the age of science and technology. Earlier, man was being controlled by the nature but now, man is controlling the natural environment. He has developed big cities, industries, agricultural lands, dams, means of transport, and communication etc. however this has caused depletion and degradation of natural environment because of the fact that he has utilized the various natural resources to a very large extent. Sustainable development means to maintain a balance between development and environment.

Following are some of the methods suggested for sustained development without depletion of natural resources and ecodegradation.
1 Reduction in man’s dependence on fossil fuels and development of alternate sources of energy like solar energy. Solar energy can be trapped by the development of photovoltaic cells, cooker, heaters etc.
2. Development of battery driven vehicles.
3. The use of biogas plants so that agricultural and animal wastes can be utilized for the production of energy.
4. The use of wind and tidal power should be explored more extensively.
5. Exploitation of sea and its resources.
6. Cultivation of more fuelwood trees and shrubs in the various areas of the land where they are not growing.
7.Recycling of Wastes.

Important principles of social responsibility

(i) To avoid misuse of national resources.
(ii) To avoid government regulation and control.
(iii) The iron law of responsibility.
(iv) To avoid class conflicts.

Social Environment : The social environment of business by certain factors like social behaviour, social interests, expectation level of education and understanding among people, social values and beliefs, social customs and traditions.  The business which neglects these factors will be subjected to criticism. A business cannot build up its image in the society without considering the social objects and values.

Cultural environment : The cultural environment is formed by the art, sahitya and life style of the people.  Arthur Millan in his Drama entitled “The Death of a Salesman” has stated that the pressure of competition influenced the thinking of a salesman in such a way that ultimately he committed suicide. The cultural values developing throughout the-world towards ‘Women’s liberation’, drug culture, youth-oriented society, etc. have influenced considerably the business policies.

The society and culture are the fundamental base of business. No business can overlook the country’s cultural heritage and values, if it wants to survive. Businessmen need to function on the basis of social expectations, desires, likes and preferences. They have to respect the human society, its cultural, values and traditions.

Describe the Tropical Cyclone and Local Storms.

Tropical Cyclones and Local Storms

Tropical cyclone representing closed low pressure system generally having a diameter of about 650 kilometres, is one of the most powerful, destructive, dangerous and deadly atmospheric storms on the planet earth. Tropical cyclones are variously called in different parts of the globe as HURRICANES in the North Atlantic Ocean (mainly in the Caribbean Sea and south eastern U.S.A.), TYPHOONS in the North Pacific Ocean (mainly in China Sea, eastern and southern coasts of China, Japan, Philippines and southeast Asia), CYCLONES in Bangladesh and eastern coastal areas of India and ‘WILLY WILLY’ in Australia.

Tropical cyclones become more disastrous natural hazards because of their high wind speed of 180 to 400 kilometres per hour, high tidal surges, high rainfall intensity (highest recorded rainfall value exceeded 2000 mm per day in Philippines) very low atmospheric pressures causing unusual rise in sea level, and their, persistence for several days or say about one week. The total cumulative effects of high velocities of wind, torrential rainfall and transgression of sea water on to the coastal land become so enormous that the cyclones cause havoc in the affected areas and thus tremendous loss of human lives and property is the ultimate result of such atmospheric deluge. The storm surge or tidal surge refers to unusual rise in sea level caused by very low atmospheric pressure and the stress of the strong gusty winds on the sea surface. These storm surges or tidal surges, when coincide with high tide, are further intensified and after intruding into the coastal land cause widespread inundation of coastal areas and great damage of human lives and property. The following case histories of a few most powerful and disastrous tropical cyclones may unravel the magnitude of destruction wrought by these natural atmospheric disturbances.

1. CYCLONIC hazards very often visit the eastern coastal areas of India and the southern coastal areas of Bangladesh. The disaster of the deadliest storm in the recorded history occurred on November 12,. 1970 in the coastal lowland of Bangladesh. This Bay of Bengal disastrous cyclone tells the magnitude of environmental hazards in respect of its killer impact on the affected people as it caused as many as 3,00,000 deaths (some sources put the figure between 300,00 and 1,000,000 deaths in Bangladesh and West Bengal of India) wherein most of the death were caused by drawing in the storm surge of oceanic water (20 feet) on the land. The official record of Bangladesh presented the total loss as death of people-200,000 missing persons-50,000 to 100,000 rendered homeless. The standing kharif crops over 1.75 million hectares were destroyed. The loss of property mounted to about 10,000 crore rupees (1000 billion rupees). The severe super cyclonic storm resulted the disruption of the supply of water and electricity. The communication system was thrown out of gear. Destruction and obstruction of roads and rails brought a grinding halt to rail and road transport which continued for weeks. Thousands of families suffered from mental agony due to separation of their kith and kins. Paradeep Port was so greatly damaged that it became unoperational for weeks. Most of the trees were uprooted. Surface and ground water was so greatly polluted due to dead bodies (both human and animal) that it became unsuitable for domestic uses and birth to the outbreak of epidemic. Though the cyclone vanished by October 31 but it left behind ugly scene of destruction and tragedy of epidemic hunger and pollution which broke the backbone of already poor inhabitants.


The northern part of the Bay of Bengal mostly the Ganga Delta Plains of West Bengal. India and Bangladesh very often suffer from frequent severe cyclonic storms and resultant storm surges (tidal waves) because of a combination of several natural conditions and phenomena such as large astronomical tides. Funneling coast configuration (spread of land from three side in arcade shape, forming the head of Bay of Bengal), low and flat terrains of coastal area and frequent occurrence of severe cyclonic storms. About 12 to 13 tropical cyclones with wind speed below 63 kilometres per hour occur every year in the northern Bay of Bengal. About 5 of these tropical cyclones become strong and severe with average wind speed of more than 63 kilometres per hour. The recurrence interval of disastrous cyclone is every five years.

2. HURRICANES very often strike the southern and the south-eastern coasts of the USA. Gulf coasts of Louisiana, Taxas, Alabama and Fonda are worst affected areas. The Galveston, Taxas (USA) disaster of September 8, 1900 tells the story of devastation caused by hurricanes in the Gulf coastal regions of the U.S.A. The terrible hurricane generated a strong storm surge (tidal wave) which raced inland and killed 6000 people mostly through drowning caused by inhumation under 10 to 15 feet (3 to 4.5m) deep water and destroyed 3000 houses. Flying planks and timbers under the force of strong gale winds also caused several deaths and damage to human structures.

It may be pointed out that Mississippi Delta Plans of the State of Louisiana (U.SA.) have the equivalence of Ganga Delta Plains of India and Bangladesh as regards the frequency and intensity of tropical cyclones but the damages mainly in the form of human causalities are far less in the former than in the latter because of more advanced and better warning systems. The Audrey Hurricane of June. 1957 struck the Louisiana Coast between New Orleans and Galveston. Though the storm was very severe as it smashed houses and floated them away, uprooted sealed concrete tombs and floated them 32 kilometres away from their resting places, but only 550 human death could be caused because of better warning systems and spontaneous response of people to the warning and predictions. In fact the water level used to rise at the rate of 1.5 feet per hour. Thus most of the people had ample time to evacuate them to safer places before the water level forced by strong storm surge could reach its peak of 8 to 12 feet (2.4 to 3.6m) above high tide water.

3. TRACY CYCLONE struck Darwin city of Australia (a coastal city of the Northern Territory) on the Christmas Day of 1974 and caused deaths of 49 persons and left 16 people missing. Thought the Tracy storm was small as the diameter of the area of gale force winds (above 63 kilometres per hour) was only about 100 kilometres but it was certainly an intense Storm as its destructive intensity was concerned. The destructiveness of the storm surge caused by this cyclone was minimized because of the fact that it occurred during a period of neap tides inspite of reduction in the intensity the Tracy cyclone damaged 80 per cent of the buildings of Darwin city having a population of 45000 people at that time (1974), caused total distuption of power supply thus plunging the entire city into darkness, put all the services of water and power supply, sanitation, transport and communication out of gear. There is little doubt that the relatively very small loss of life in Darwin (city) can be attributed to the fact that the cyclone was accompanied by a restricted storm surge effect; major damage was produced by high winds and torrential rain. Nevertheless, the problems encountered in Darwin, serve to highlight the magnitude of the tropical cyclone danger in much more densely populated areas of developing rather than developed countries (i.E. Hobbs, 1980).

4. LOCAL STORMS The severe local storms of hazardous nature include TORNADOES (which affect the southern and the eastern USA) and thunderstorms. Tornadoes, though smallest in area of all the hazardous atmospheric storm, are very deadly to human lives and property. On an average the annual toll caused by tomatoes in the U.S.A. includes damage to property worth, 100,000,000 dollars and 150 human deaths. The deadliest part of the tornandoes is the TORNADO MISSLILES (consisting of uprooted trees, their branches, roofs of buildings etc. which are carried away by dynamic force of winds) which inflict great damage to buildings, other human structures and human lives. A tornado for example at Lubbock (Texas. U.S.A.) in 1970 moved a long cylindrical fertilizer tank (3.35 m x 12.5 mm size with a weight of 11 tons) for a distance of 1.21 km. from its original place.

Two great seasons of tornado outbreak in the U.S.A. tell the awful story of ravages caused by deadly tornadoes. The occurrence of tornadoes in groups hazardous but when very hot and dry days prevail for a few weeks in continuation, environmental hazard in the form of heat waves occurs which affect the environment and human lives, plants and animals. The persistence of exceptionally cold conditions for several days causes severe snowfall. A dry season a year may not be as much disastrous as continued dry seasons for several years. The perception and concept of drought vary from place to place and from one group of people to other group based on profession and occupation. In fact, drought occurs when there is appreciable decrease in rainfall from the average normal rainfall. Floods are still very severe environmental hazards which are related to atmospheric processes. Mississippi flood plains (U.S.A.) and the Ganga Plains (India) are frequented by severe flood hazards. It may be pointed out that floods are not always hazards rather these are also boom because these bring rich fertile alluvial soils each time and thus increase agricultural productivity.

What are Earthquake Hazards (Disasters).

Earthquake Hazards / Disasters

An earthquake is a major demonstration of the power of the tectonic forces caused by end genetic thermal conditions of the interior of the earth. An earthquake is motion of the ground surface, ranging from a faint tremor to a wild motion capable of shaking building apart and causing gaping fissures to open in the ground. The earthquake is a form of energy of wave motion transmitted through the surface layer of the earth in widening circles from a points of sudden energy release the focus.

The magnitude or intensity of energy released by an earthquake is measured by the RICHTER SCALE devised by Charles F Richter in 1935. The number indicating magnitude or intensity (M) on Richter scale ranges between 0 and 9 but in fact the scale has no upper limit of number because it is a logarithmic scale. It is estimated that total annual energy released by all earthquakes is about 10 25 ergs, and most of this is from a small number of earthquakes of magnitude over 7’ (A.N.Strahler and A.H. Strahler, 1976). The 1934 Bthar earthquake (India) measuring 8.4 magnitude on Richter Scale and Good Friday Earthquake of March 27, 1964. in Alaska, U.S.A. measuring 8.4 to 8.6 on Richter Scale may help in assessing the devastation caused by the energy release during earthquakes of varying magnitudes. The World’s largest and most intensive recorded earthquake was of the magnitude of 8.9 and the number of recorded earthquakes increase 10 times as magnitude decreases by one.


The quakes of magnitude 5.0 equal in energy to ordinary atomic
bomb. The atomic bomb hurled over Hiroshima (Japan) during
Second World War equaled the magnitude of 5.7 on Richter
Scale. The energy released from such earthquakes equals 8 x
1020 ergs.

Another scale of the measurement of the degree of destructiveness or intensity of earthquakes is MERCALLI SCALE. The degree of destructiveness on intensity of an earthquake depends on a variety of factors e.g. magnitude, distance from epicenter, acceleration, duration amplitude of waves, type of ground, water table, nature of geometries of the region concerned and the nature and type of constructions (such as building made of wood or bricks, earthen buildings made of muds, tin shades, huts etc.) affected by an earthquake.

The place of the origin of an earthquake is called FOCUS which is always hidden inside the earth but the depth of which varies from place to place. The deepest earthquake may have its focus at a depth of even 700 km. below the ground surface but some the major Himalayan earthquakes, such as the Bihar-Nepal earthquake of August 21,1988, had their focus around 20-30 km. deep. The place on the ground surface, which is perpendicular to the buried focus’ or hypocenter’ recording the seismic waves for the first time is called EPICENTRE. The seismic waves move away from the source of the earthquake (focus or hypocenter) in the form-of (1) primary or Pressure waves (P waves), (2) Secondary, Shear or Transverse waves (S waves) and (3) Long waves or surface waves (L waves). These seismic waves are recorded with the help of an instrument called SEIMOGRAPH or SEISMOMETER at the epicenter. The patterns of recorded seismic waves are studied and various definite information about the centre of the origin of the earthquake (focus or hypocenter), magnitude and destructive power of the earthquake etc. are received.

Magnitude and energy released during an earthquake is generally related to the effects of the earthquake in terms of human beings and his habitats. It is apparent from table that most of the earthquakes occurring on the earth are small. On an average about 80,000 earth tremors are recorded by seismographs each year but most of them are not felt by human beings. Beno Guttenburg and Charles F.Richter have stated that the size (magnitude M) and the logarithm of frequency (number of earthquakes N) of earthquakes in a given area of observation are linearly related. On the basis of this analysis one can calculate the probable return periods of earthquakes, or different magnitudes. Great earthquake, with magnitudes over 8, generally occur about once every 5 to 10 years. Earthquake of magnitude 8 or more has a probable return period of 50 years in North-East India. Real damages caused by earthquakes begin at magnitude 5 and continue to increase to nearly total destruction in the neighbouring settlements by the earthquakes with more than 8 magnitude. Maximum recorded magnitude is 8.9.

What are the main causes of Land Slide?

Main causes of Land Slide

Land slide is a natural problem. In high rain when areas when the big rocks come down with water we call it, land-slide. There are many. reasons of land slide:

(1) In hill area due to undeveloped of trees comes this situation.

(2) If we don’t dig the mines in proper way, this situation will come.

(3) Due to earth quake, spoil the balance of land, cutting of trees, this situation comes.

(4) Due to earthquake and volcano and the land slide happens.

(5) Sometime human activities are responsible for land-slide as mining,
tree cutting etc.

 Write an essay on Green House Effect?

A glass house used for raising delicate plants is called Green House. A green house has higher temperature inside than outside though the interior receives less radiations. It is called Green House Effect. The factors which contribute to this effect are (i) glass walls (ii) high carbon dioxide content and (iii) high water vapour content of the air in the Green House. They let the short wave radiations (wave length 0.15-4.0 pm) pass through them but prevent the passage of long wave (infra red) radiations emitted by the earth’s surface. This makes inside of the Green House warmer than outside.

In the context of environment, Green House effect refers to ‘selective energy absorption by some atmospheric gases, which allow short wave length energy to pass through but absorbs longer wave lengths and reflect heat back to earth’. The atmospheric gases which are permeable to short wave solar radiations, but are strong absorber of long wave radiations emitted from the surface of earth are called Green House gases. These include carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, ozone and water vapour. Though carbon dioxide contributes maximum to the Green House effect on the earth, methane (CH) and chlorofluoro carbons (CJ Cs) are potent Green House gases even though their contributions in the atmosphere are much less than that of carbon dioxide. Carbon dioxide is chiefly produced by the burning of fuels. It is also released by plants and animals during the process of respiration. Methane is the primary component of natural gas and it emanates from garbage dumps, swamps and rice fields. Chlorofluorocarbons are used around the world as refrigerants, aerosol propellants, in isulators and fire extinguishers. These gases are responsible for about 15 per cent of the green House Effect.

Nitrous oxide (N2O) is produced during the process of destruction of ozone layer in the stratosphere. The ozone in the stratosphere acts as a protective layer, because it absorbs much of the ultra violet radiation from the sun. however, its higher Concentration in troposphere acts as a Green House gas. It is responsible for about 10-20 percent of the Green House effect.