• It is sudden shake-up of the earth’s surface due to disturbance beaneath the surface.
  • The point of origin of earthquake is called Seismic focus. Most of the earthquakes originate at the depth of 50-100 km inside the earth.
  • The point on the earth’s surface vertically above the earth’s surface is called Epicentre.
  • The passage of earthquake waves in recorded by Seismograph.
  • The magnitude of waves is measured on Richter’s scale.
  • Types of Waves: 1. Primary Waves (P-Waves), 2. SecondaryWaves(S-Waves), 3. Surface Waves or Long Waves (L-Waves)
  • The principal earthquake regions are-(1) Circum Pacific Belt (2) Mid World Belt (3) Volcanic zone.