EARTH QUAKE

Earthquake
== '''A sudden movement of the earth's crust caused by the release of stress accumulated along geologic faults or by volcanic activity. It is also called seism, temblor. causes of earthquake: The short answer is that earthquakes are caused by faulting, a sudden lateral or vertical movement of rock along a rupture (break) surface. The surface of the Earth is in continuous slow motion. This is plate tectonics--the motion of immense rigid plates at the surface of the Earth in response to flow of rock within the Earth. The plates cover the entire surface of the globe. Since they are all moving they rub against each other in some places ,sink beneath each other in others, or spread apart from each other. At such places the motion isn't smooth--the plates are stuck together at the edges but the rest of each plate is continuing to move, so the rocks along the edges are distorted. As the motion continues, the strain builds up to the point where the rock cannot withstand any more bending. With a lurch, the rock breaks and the two sides move. An earthquake is the shaking that radiates out from the breaking rock.Effects of an earthquake:''' == Destructive Effects:

'''1.Earthquake causes dismantling of buildings, bridge and other structures at or near epicenter. Many men and animals are killed or buried under collapsed houses.'''

'''2.Rails are folded, underground wires broken. Fire breaks out inevitably in large towns.'''

3.Earthquakes originate sea waves called Tsunamis.

4.Earthquakes result in the formation of cracks and fissures on the ground formation.

5.The earthquakes cause landslides and disturb the isostatic equilibrium.

6.Landslide due to earthquake may block valleys to form lakes.

Constructive Effects:

1.Sometimes the earthquakes cause formation of hot springs which are very useful to people.

2.The earthquakes sometimes cause submergence in coastal land, and result in formation of inlets, bays and gulfs which help to develop of fishing and shipping etc.

3.Sometimes, the earthquakes cause emergence of costs and bring fertile shore out of water to give chance to develop crop production.