Earthquakes

They are natural phenomena characterized by the sudden shaking or trembling of the Earth’s surface. They result from the release of energy in the Earth’s lithosphere, which create seismic waves.
Causes:
1.Tectonic Plate Movements
2.Volcanic Activity
3.Human Activities like mining, reservoir-induced seismicity
4.Landslides and Collapses
Epicenter is the point on the Earth’s surface directly above the earthquake’s origin. Focus is the point inside the Earth where the earthquake originates. Seismic waves are of Primary waves, Secondary waves, Surface waves.
Magnitude of Earthquake is measured using Richter Scale and Intensity is measured using Mercalli Scale
India is divided into 4 seismic zones such as Zone V (Very High risk), Zone IV (High risk), Zone III (Moderate Risk), Zone II (Low Risk)
Major Earthquakes in India:
1.Gujarat Earthquake-2001
2.Kashmir Earthquake-2005
3.Bihar-Nepal Earthquake-1934
4.Latur Earthquake-1993
5.Assam-Tibet Earthquake-1950
National Disaster Management Authority formulates policies and guidelines for earthquake preparedness.