Learn with NITISH KUMAR

■ Earthquake: • An earthquake in simple words is the shaking of the earth. It is a natural event. It is caused due to release of energy, which generates waves that travel in all directions. • The point where energy is released is called the focus or hypocentre. The point on the surface of the earth which is vertically above the focus is called the epicentre. • The vibrations called seismic waves are generated from earthquakes that travel through the Earth and are recorded on instruments called seismographs. All natural earthquakes occur in the lithosphere. • The velocity of waves changes as they travel through materials with different densities. The denser the material, the higher is the velocity. Their direction also changes as they reflect or refract when coming across materials with different densities. • 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. • The largest ever earthquake was 9.5 recorded in Chile in 1960. □ Causes for Earthquakes: • Due to the movement of loose fragmented pieces of land on earth’s crust knowns as tectonic plates. •  Volcanic eruption. • Man-made activities like explosion of chemical or nuclear devices, the roofs of underground mines collapse causing minor tremors. □ Types of Earthquake waves: • Earthquake waves are of two types. They are Body waves and Surface waves. • Body waves are generated due to the release of energy at the focus and move in all directions travelling through the body of the earth. • The body waves interact with the surface rocks and generate new set of waves called surface waves. These waves move along the surface. • There are two types of body waves. They are called P-waves and S-waves.  • Primary waves (P 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. These waves tend to vibrate parallel to the direction of wave propagation. • Secondary waves (S waves): 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. The direction of vibration of this S-wave is perpendicular to the direction of wave propagation. • When an earthquake occurs, there is a zone on the opposite side of Earth where S-waves are not measured. • This S-wave shadow zone begins 103° on either side of the earthquake. • There is also a P-wave shadow zone on either side of the earthquake, from 103° to 150°. □ How it is measured? • Richter scale is used to measure the magnitude of the earthquake. It is expressed in the range of 0-10. • Nowadays, magnitude of earthquakes are measured on a scale called the Moment Magnitude Scale (MMS). This has replaced the better known Richter scale, now considered outdated and less accurate. • MMS measures the movement of rock along the fault. It accurately measures larger earthquakes, which can last for minutes, affect a much larger area, and cause more damage. • The Moment Magnitude can measure the local Richter magnitude (ML), body wave magnitude (Mb), surface wave magnitude (Ms). • The Mercalli scale is used to measure the intensity of an earthquake. It measures the visible damage caused due to the quake. It is expressed in the range of 1-12.

■ QR code-based Coin Vending Machine (QCVM): • To improve the distribution of coins among members of the public, the Reserve Bank of India (RBI) is preparing a pilot project on QR code-based Coin Vending Machine (QCVM) in collaboration with a few leading banks. • The QCVM is a cashless coin dispensation machine which would dispense coins against a debit to the customer’s bank account using Unified Payments Interface (UPI). • Unlike cash-based traditional Coin Vending Machine, the QCVM would eliminate the need for physical tendering of banknotes and their authentication. • Customers will also have the option to withdraw coins in the required quantity and denominations in QCVMs. • The pilot project is planned to be initially rolled out at 19 locations in 12 cities across the country. • These vending machines are intended to be installed at public places such as railway stations, shopping malls, marketplaces to enhance ease and accessibility.