JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III ELEMENTS OF EARTHQUAKE ENGINEERING Previous Question Paper (February - 2023 - R18)

The two major factors responsible for the occurrence of earthquakes are:

1. Tectonic Plate Movements: The constant movement of the Earth's lithospheric plates, caused by convection currents in the mantle, leads to the accumulation of stress along plate boundaries. When this stress exceeds the strength of the rocks, a sudden release of energy occurs, resulting in an earthquake.
2. Faulting: The displacement of rock masses along existing fractures or faults in the Earth's crust causes rapid energy release. This movement can be triggered by tectonic forces, volcanic activity, or human-induced activities like reservoir-induced seismicity.

The Magnitude of an earthquake is a quantitative measure of the energy released at the source, typically determined using the Richter scale or Moment Magnitude scale. It is a single, objective value that remains constant regardless of the observer's location.

In contrast, the Intensity is a qualitative measure of the effects and damage caused by the earthquake at a specific location, usually assessed using the Modified Mercalli Intensity (MMI) scale. Intensity varies significantly depending on the distance from the epicenter, local soil conditions, and the quality of construction.