Cause of earthquakes

Earthquakes are caused due to disequilibrium in any part of the crust of the earth. A number of caused have been assigned to cause disequilibrium in the earth's crust such as volcanic eruptions, faulting and folding, up warping and down warping, hydrostatic pressure of man-made water bodies like reservoirs and lakes, and late the plate movements. The occurrence of severe devastating earthquake of San Fransisco (U.S.A) in 1960 led H.F. Reid, one of the official investigators of San Fransisco Earthquake Disaster, to advance his important ELASTIC REBOUNB THEORY to explain the mode and causes of earthquake mainly caused by fractures and faults in the earth's crust and upper mantle. Recently, PLATE TECTONIC THEORY has been accepted as the most plausible explanation of earthquakes.

Natural hazards

Natural environmental hazards and disasters involve comparatively rare high-intensity processes and extreme events caused by both terrestrial and atmospheric processes. The study of natural hazards includes the consideration of identification of specific events, finding of their causative factors, assessment of their impacts on human and other biological communities, prediction of such events and finding their remedial measures. Natural hazards fall in two broad categories (1) planetary hazards and (2) extra-planetary hazards or extra-terrestrial natural hazards.

Aspect and approaches to environmental management

On an average environmental management involves (1) judicious and gainful utilization of natural resources for socio-economic development and (2) Maintenance of environmental quality by perusing ecological principle. Broader objectives of environmental management include (i) to restrict and regulate the exploitation and utilization of natural resources, mainly non-renewable natural resources; (ii) to regenerate degraded environment and to renew natural resources (iii) to control environmental degradation and pollution (iv) to reduce the impacts of extreme events and natural disaster (v) to make optimum utilization of natural resources by recycling and reusing waste materials produced from one activity to another economically and environmentally viable activity (vi) to review and revise the existing technologies of production in terms of their adverse effects on the environment (vii) to formulate laws and regulations for the implementation of environment protection and conservation programs to maintain the environment quality.

International Co-operations for Environmental Management

The international communities are well aware and seized of global environmental and ecological problems and various efforts have been initiated to control global warming and halt probable climate change. There are several organization, government agencies, intergovernmental agencies, non-government organizations (NGO) which have undertaken various action plan and projects to study the relationships between man and environment interactions between man and nature, the environmental problems resulting there from and remedial measures therefore.

Major Global Problems

The most significant global environment problem faced by the world community is related to global environmental changes consequent upon global warming resulting from a host of causal factors viz. ozone depletion, emission of greenhouse gases at alarming increasing rate, deforestation etc. the probable net result of global warming would be climatic change at local, regional and global levels.

Acid Rain

Acid rain fall-out of acids caused by sulphur dioxide and nitrogen oxides with rainfall and thus increases in the amount of acidity of rainwater. As pointed   out above rainwater is not pure because atmospheric carbon dioxide is dissolved in the rainwater which thus because moderately acidic, the pH being generally 5. The water with Ph value of 7.0 is called neutral water whereas the pH value below it makes the water alkaline. The water becomes more injurious when the pH fall below 4.

Sulphur dioxide emitted from man made sources in large quantities into the atmosphere combines with water to form sulphur and sulphuric acids (H2SO4). These acids fall on the earth's surface with rainfall and thus the fall of highly acidic water are called acid rain. The pH of rainwater in some localities of the USA mainly in West Virginia has gone down to 1.5 pH of rainwater in Europe is as low as 2.4 whereas the normal range of pH of neutral water must be 7.0.

The main sources of acid rains are oxides of sulphur and nitrogen which are emitted from industrial establishments and different types of vehicles. These pollutions are spread in atmosphere by wind and from acids after reacting with water in the atmosphere. It may be pointed out that acid rains are not confined to the source areas of the emissions of oxides of sulphur and nitrogen rather they cover much larger areas far away from the source pollutants being in gaseous phase are carried away and spread over larger areas through winds and clouds. For example, oxides of sulphur and nitrogen spewed from several mills in Germany and U.K have caused widespread acid rains in Scandinavia countries with the result most of the lakes in Scandinavia countries have lost their biological communities and are now biologically termed as dead lakes.

Dead lake means destruction and death of all aquatic lives including plants and animals in lakes, ponds, and rivers. Acid rains also affect human community adversely, though the mode of human disease and death due to acid rains has not been properly understood as yet. The productivity of soils is also significantly lowered because of acid rains as increased acidity destroys mineral elements and other nutrients of the soils.

Acid rain is not a local problem or a problem of a particular country, rather it is an international problem because air pollutants emitted from a particular country are carried in the atmosphere by the winds and are spread over other countries. Thus the problem of acid rains should be tackled at international level.

World Common Environmental Issue

Present world is facing many environmental hazards and being problematic living support system of entire living beings. Environment is the common house for entire living and non-living things. But, the right of the other except man is losing by the human self-fish activities. Declining environmental condition is common concern matter all developed and developing countries that made think about improvement of environment condition for sustainable development and balance between sources and human. As a result many international conferences are held in order to manage environment depletion condition. These conferences find out the common issues and declare to manage.

1 Global change: - climate change, global warming, ice melting and sea level rising, change in atmosphere gaseous composition, change in water, air and soil quality, land use change, ecosystem services change and life system change.

2 Technological and Toxic Hazards, Incidence of disease infection

3 Natural resource degradation, life support bio-resource deletion, deforestation, desertification and land degradation

4 poverty, regional disparity, and inequality of development pattern

5 Loss of biodiversity and threat to cultural heritage

6 Solid waste management and technological appropriateness

7 Regional cooperation and world unity for long term solution