Earthquake in Sikkim; tremors felt in 4 States
#GS3 Disaster Management
An earthquake measuring 5.4 on the Richter scale struck the Sikkim-Bhutan border at 8.49 p.m. on Monday, with tremors being felt in Assam, West Bengal, and Bihar.
- An earthquake which is a natural event is the shaking of the earth mainly caused due to release of energy, which generates waves that travel in all directions.
- The point below the earth’s surface where the earthquake starts is called the hypocenter
- The location directly above it on the surface of the earth is called the epicenter.
Different types of Earthquakes
- Tectonic Earthquakes: Tectonic plates (Lithospheric plates) are constantly shifting as they drift around on the viscous, or slowly flowing, mantle layer below. This non-stop movement causes stress on Earth’s crust. When the stresses get too large, it leads to cracks called faults.
- Volcanic Earthquake: It is confined to only regions of volcanic activity. The nature of the quake is similar to tectonic earthquake.
- Human Induced Earthquakes: In the areas of intense mining activity, sometimes the roofs of underground mines collapse causing minor tremors. These are called collapse earthquakes.
Measurement of Earthquakes
- The energy from an earthquake travels through Earth in vibrations called seismic waves.
- Scientists can measure these seismic waves on instruments called seismometers.
- The earthquake events are scaled either according to the magnitude or intensity of the shock. The magnitude scale is known as the Richter scale. The magnitude relates to the energy released during the quake. The magnitude is expressed in absolute numbers, 0-10.
- The intensity scale is named after Mercalli, an Italian seismologist. The intensity scale takes into account the visible damage caused by the event. The range of intensity scale is from 1-12.
Earthquake in India
- India is one of the highly earthquake affected countries because of the presence of technically active young fold mountains - Himalaya.
- India has been divided into four seismic zones (II, III, IV, and V) based on scientific inputs relating to seismicity, earthquakes occurred in the past and tectonic setup of the region.
Source: The Hindu