1. Defintion of Earthquake
  2. Tremor
  3. Epicentre
  4. Shock Waves
  5. Causes of Earthquakes


Definition of Earthquakes

These are sudden movement or vibrations in the earth crust. They occur as a result of disturbance within, and below the earth crust. The transmission of the resultant vibrations outward to the surface, leads to a series of shocks waves that give rise to earthquakes.

The point at which the shock originates is called the origin or focus and the point on the earth surface directly above the origin or where the shock wave first hit the surface is called epicenter. The instrument used in measuring the intensity of earthquakes is called seismograph.

Earthquakes could be disastrous where there are densely populated areas.


Earth tremors are vibrations within the earth’s crust produced by gentle waves. However, earth tremors are not severe as earthquakes. Its only occurs every few minutes.


This is the point on the earth’s surface where the shock waves first hit the surface.

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