Earthquakes are caused mainly due to dis-equilibrium in any part of the crust of the earth. A number of causes have been assigned to caused dis-equilibrium or isostatic imbalance in the earth’s crust.
Earthquake: An earthquake is shaking or trembling of the earth’s surface, caused by the seismic waves or earthquake waves that are generated due to a sudden movement in the earth’s crust or upper mantle.
Reasons of earthquake: There are two reasons of earthquake are as follows:
(a) Natural Reasons
- Volcanic eruption : Volcanic earthquakes are caused by slip on a fault near a volcano. Volcanoes are often found in areas of crustal weakness and the mass of the volcano its self adds to the regional strain.
- Faulting and folding : The plate boundaries are made up of many faults, and most of the earthquakes around the world occur on these faults. Earthquakes are caused by a sudden release of stress along these faults in the earth’s crust.
- Upwarping and downwarping
- Gaseous expansion and contraction inside the earth.
- Plate Movement
- Landslides
(b)Man-made/Anthropogenic Reasons
- Deep underground mining
- Blasting of rock by dynamites for construction purposes.
- Deep underground tunnel
- Nuclear explosion
- Reservoir Induced Seismicity (RIS) (E.g. Koyna Reservoir witnessed Earthquake in 1967 due to RIS)
- Hydrostatic pressure of artificial water bodies like reservoirs and lakes.
Plate tectonics provides the most logical explanation of volcanoes and earthquakes.
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