Earthquakes And Its Causes


 
 
Concept Explanation
 

Earthquakes And Its Causes

Earthquakes: An earthquake is a major demonstration of the power of the tectonics forces caused by endogenetic thermal conditions of the interior of the earth. It is a form of energy of wave motion transmitted through the surface layer of the earth in widening circles from a point of sudden energy release, the focus. The magnitude or intensity of energy released by an earthquake is measured by the Richter scale. This scale has no upper limit of number because it is logarithmic scale.The place of origin of an earthquake is called focus, which is always hidden inside the earth but its depth varies from place to place. The place on the ground surface, which is perpendicular to the buried 'focus' or 'hypocentre', recording the seismic waves for the first time is called epicentre. The waves generated by an earthquake are called 'seismic waves', which are recorded by an instrument called seismograph. The science that deals with the seismic waves is called seismology.

Causes of Earthquakes: Earthquakes are caused mainly due to disequilibrium in any part of the crust of the earth. A number of causes have been assigned to cause disequilibrium or isostatic imbalance in the earth's crust such as volcanic eruptions, faulting and folding, upwarping and downwarping, gaseous expansion and contraction inside the earth, hydrostatic pressure of man-made water bodies like reservoirs and lakes, etc. Elastic Rebound Theory of H.F. Reid provides an excellent explanation of these processes and factors.

Distribution of Earthquakes: A detailed study of the earthquake clarifies that they are intimately related to the converging plate boundaries. The Pacific Ring of Fire is the manifestation of the same fact where more than 65% of the world's earthquakes and volcanic eruptions take place. That is why the countries located along the borders of the Pacific like Chile, Peru, Ecuador, Japan, Philippines etc. are more prone to these disasters

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