Earthquake is a sudden earth movement or vibration in the crust. The scientific study and interpretation of the earthquake is known as Seismology and waves generated by the earthquake farmed as Seismic waves. The point at which an earthquake originates is called Focus or Origin and sometimes it is several kilometers bellow the surface. The point on the earth’s crust immediately above focus is called Epicenter (this is the point where the shock waves hit first and give rise to an earthquake). Thr main causes of earthquake are;-
(a) Movement or sliding of tectonics plate over the other causes faulting of the lithospheric plate, when tectonics plates meet they cause stress and fracture of the crustal rocks. This sudden action causes releases of energy which generate shock waves which shake the earth.
(b) Volcanic eruption or movement of magma bellow or on the earth surface where Hugh pressure in the crust pushes out magma strong and causes vibration, most earthquake originates from the mantle.