Context: The Union minister for science and technology has informed Lok Sabha that around 59% of the landmass of India (covering all states) is prone to earthquakes of different shaking intensities.

About Earthquake

• An earthquake is the shaking of the surface (occurs without warning) of the Earth resulting from a sudden release of energy in the Earth’s lithosphere that creates seismic waves.

• It is tectonic in origin and results from the release of accumulated stress of the moving lithospheric or crustal plates.

• The earth’s crust is divided into seven major plates (and several minor plates), which move slowly and continuously over the earth’s interior.

• Causes of earthquakes can be natural (tectonic, volcanic) and anthropogenic (mining activities, construction of dams, nuclear-chemical explosions).

• The occurrence of an earthquake in a populated area may cause numerous casualties and injuries as well as extensive damage to property.

Earthquake waves are basically of two types

Body waves: Generated due to the release of energy at the focus and move in all directions travelling through the body of the earth. There are two types of body waves. They are called P and S-waves.

• P-waves move faster and are the first to arrive at the surface. These are also called ‘primary waves’. The P-waves are similar to sound waves. They travel through gaseous, liquid and solid materials.

• S-waves arrive at the surface with some time lag. These are called secondary waves. An important fact about S-waves is that they can travel only through solid materials.

Surface waves (most damaging): The body waves interact with the surface rocks and generate new sets of waves called surface waves, which move along the surface.

• Shadow zones: These are specific areas where the waves are not reported by seismograph.

About Earthquake Risk in India

• According to the seismic zoning map of India prepared by the Bureau of Indian Standards (BIS), India has been divided into four zones – II, III, IV and V.

• Zone V is seismically the most active region while Zone II is the least.

• Around 11% of the country falls in Zone V, 18% in Zone IV, 30% in Zone III and the remaining in Zone II.

What is the other news covered in the article?

• Coal-based power: Over the years, the share of coal in the total primary energy mix has increased from about 42% in 2009-10 to 45.56% in 2020-21.

• More than 72% of the electricity generated in the country is coal-fired (including lignite).

• Landless tribal households in northeast India: According to the Socio-Economic and Caste Census (SECC) 2011 report, around 59% of rural households in northeast India have no land.