An earthquake is a sudden shaking and trembling of the earth. This shaking and trembling causes the movement of a series of shock waves on the earth’s surface.
Earthquakes are caused by the sudden breaking and movement of the tectonic plates of the earth's rocky outermost crust. Earthquakes typically occur on plate boundaries.
Every earthquake has a focus and an epicentre. The epicentre of an earthquake is the location on the earth’s surface where the damage from an earthquake is the maximum. The point of origin of an earthquake is its focus.
An earthquake results in a series of shock waves on the earth’s surface. These shock waves are called seismic waves. A seismograph records the vibrations of the seismic waves caused by an earthquake.
There are three types of earthquake waves or seismic waves.
- P waves or longitudinal waves.
- S waves or transverse waves
- L waves or surface waves
The Richter scale is used to measure the intensity of an earthquake.