What is Earthquake

 Know everything about earthquake, what, why and how?  sanjeev sir

 Essay on earthquake in English 

 Essay on earthquake in hindi |  Essay on earthquake in hindi

 Earthquake is called shaking or tremor due to the sudden release of tension on the earth's crust.  Earthquakes are the most disastrous disaster of natural disasters that can cause the loss of human life.  The impact of earthquakes usually occurs over a very wide area.  Earthquakes cause widespread devastation along with injuring and causing deaths.  Due to the sudden and rapid pace of this catastrophe, the public does not get time to rescue it.

 During the last two decades of the twentieth century, 26 major earthquakes occurred in different places of the Earth, causing untimely deaths of about one and a half million people globally.  It is unfortunate that, despite the result of the earthquake being very widespread, it has not yet been able to make accurate predictions about it.  For this reason, some steps are taken according to the possible response to this disaster.

 What is seismology?  Seismology

 The branch of science under which earthquakes are studied is called seismology and scientists who study seismology are called seismologists.  The English word 'seismology' is the Greek word prefixed 'seismo' which means earthquake.  Seismologists measure the magnitude of an earthquake by basing its magnitude.  There are several methods of measuring the magnitude of an earthquake.

 Why does an earthquake occur?  Why does an earthquake happen

 Our earth is mainly made up of four layers, inner core, outer core, mantle and crust.  The crust and upper mantle are called lithospheres.  This 50-kilometer thick layer is divided into squares, called tacatonic plates.  These tectonic plates keep moving from their place but when they move too much, earthquake occurs.  These plates can move from their place, both horizontally and vertically.  After this, they find their place and in such a situation one plate falls under the other.

 Definition of Earthquake |  Definition of earthquake

 Earthquake can be defined as the occurrence of the shaking of the earth's surface due to accidental release of tension generated in the earth's crust.  Due to this stress, a slight vibration in the Earth can cause widespread destruction in a wide area when a slight vibration occurs.

 The point at which an earthquake occurs is the seismic focal point and the point on the surface of the earth just above it is known as the epicenter or the center.  The position of the epicenter is expressed by the latitudes and longitudes of that place.

 

 A slight shock is felt during the earthquake.  Then after some interval a wavy or jerky vibration is felt, which is more powerful than the first shock.  During small earthquakes the land trembles for a few seconds, but in large earthquakes the duration may be more than a minute.  During the 1964 Alaska earthquake, the earth was shaking for about three minutes.  Earthquake period due to earthquake depends on various reasons like distance from epicenter, soil condition, height of buildings and materials used in their construction.

 Earthquake intensity measurement |  Earthquake intensity measurement unit

 The Richter scale is used to measure earthquake intensity.  This is called the Richter Magnitude Test Scale.  Earthquake waves measure on a Richter scale from 1 to 9.  The Richter scale scale was discovered in 1935 by Charles Richter, a scientist working at the California Institute of Technology, in collaboration with Beno Gutenberg.

 Under this scale, the intensity of an earthquake increases by 10 times per scale and the energy released during an earthquake increases by 32 times per scale.  This simply means that the magnitude of the earthquake on the 3 Richter scale would increase 10 times the 3 Richter scale on the 4 scale.  The magnitude of the earthquake on the Richter scale can be gauged from the fact that an earthquake on the 8 Richter scale can generate energy emanating from 6 million tons of explosives.

 

 In addition to Richter, the Merkeli scale is also used to measure earthquakes.  But in this, earthquakes are measured on the basis of strength rather than intensity.  It is less prevalent as it is considered less scientific than Richter.  Several reasons can be responsible for the damage caused by earthquakes, such as poor structure of houses, poor structure, type of land, population settlements etc.

 

 How soon do earthquakes come?  |  How soon do earthquakes come?

 

 Earthquakes are a common occurrence.  According to an estimate, somewhere in the world about 87 seconds, the earth shivers lightly.  These tremors can be felt but they are not powerful enough to cause any kind of damage.  An average of 800 earthquakes occur on the earth every year, causing no damage.  In addition to this, there are 18 major earthquakes every year on Earth, along with an extreme earthquake.

 Rarely, earthquakes can occur in different groups of earthquakes during a short time span.  For example, during the seven weeks (16 December 1811, 7 February, and 23 February 1812) in New Madrid, the United States, three intense earthquakes occurred.  Similarly, three intense earthquake events occurred during a 12-hour period on 22 January 1988 in Tenet Creek, Australia.

 

 What are the types of earthquakes?  what are the different types of earthquakes |  Types of Earthquakes & Faults |  major types of earthquakes

 There are mainly two types of earthquakes -

 Natural earthquake

 Naturally occurring earthquakes are also called tectonic earthquakes because they are related to the tectonic properties of the Earth.  Most of the naturally occurring earthquakes are accompanied by faults.  A rupture is a crack or rupture caused by movement in the crust.  These fractures can be anywhere from a few millimeters to several thousand kilometers.  During the geology chronology most of the faults form double emplacements.

 Earthquake inspired by human activities  Human activity can trigger earthquakes, but how many?  |  Can earthquakes be caused by human activity | Human induced earthquakes |  Man made earthquake in india

 

 Human activities can also induce earthquakes.  Extraction of oil from deep wells, filling or draining waste material or any liquid in deep wells, building huge dams holding vast amounts of water and activities similar to catastrophic events such as nuclear explosions can cause human induced earthquakes.

 One of the major earthquakes due to artificial reservoir occurred in the Koyna region of Maharashtra in 1967.  Another notorious human activity that caused the earthquake has been related to the entry of liquids into deep wells in the Denver area on the Rocky Moutain in Colorado, USA.

 How do earthquakes occur?

 According to the plate tectonic theory, the outer layer of the earth or the crust is shaped like a jigsaw saw made of large and small rigid plates.  The thickness of these plates can be up to hundreds of kilometers.  These plates move relative to each other, probably due to the effect of convection currents below the cavity.  The Earth is divided into several seismic plates.  On the difference of these plates, where the plates collide or move away from each other, large landmasses are found.  The speed of these plates is quite slow.  Mostly severe earthquakes occur where these plates are found together.  Sometimes it also happens that the edges of the plates get stuck in each other, due to which it is unable to move and pressure is created between them.  As a result, the plates slide into each other with a heavy blow and the earth vibrates fiercely.  In this process, the earth's crust breaks due to huge errors.

 Once an area has developed defects, the area becomes weak.  Earthquakes are actually a means of exiting the accumulated stress inside the Earth, which are usually confined within the confines of these debris.  New stresses arise when the stress inside the earth is released to some other location away from the fault.

 How to find the power of earthquake?

 There are two ways to measure the magnitude and intensity of an earthquake.  The magnitude of the earthquake is measured on the basis of ground waves recorded in the earthquake.  Earthquake-prone is an earthquake detection device.  The intensity of an earthquake is determined by the maximum amplitude of the signals recorded in the earthquake and the distance of the instrument from the earthquake site.

 Richter scale intensity effect

 0 to 1.9 shows only from the seismograph.

 2 to 2.9 Light Vibration.

 3 to 3.9 Feeling like a truck passes near you

 

 4 to 4.9 windows may break.  Hanging frames can fall on walls.

 5 to 5.9 furniture can move.

 The foundation of 6 to 6.9 buildings can be cracked.  Upper floors may suffer damage.

 7 to 7.9 buildings collapse.  Pipes burst inside the ground.

 Large bridges including 8 to 8.9 buildings also collapse.

 Complete destruction due to 9 and above.  If someone stands in the ground, he will be seen waving the earth.  If the sea is close, there is a possibility of a tsunami.

 The Richter scale starts with one unit but no end has been fixed, although the intensity of the most powerful earthquake known so far has been measured between 8.8 to 8.9.

 

 The magnitude of the strongest earthquake that has occurred in India so far has been measured at 8.7 on the Richter scale, the earthquake struck on 12 June 1897 in the Shillong Plate.

 Seismic zone of india

 India is divided into five different seismic zones.

 Area I where there is no danger.

 Region II where there is less danger.

 Region III where there is an average threat.

 Area Iv where there is more danger.

 Area v where there is too much danger.

 All states of North-East, Jammu and Kashmir, Uttarakhand and parts of Himachal Pradesh fall under Zone-5 itself.  From low altitude parts of Uttarakhand to most parts of Uttar Pradesh and Delhi fall in Zone-4.  Central India falls under relatively low danger zone zone-3, while most of the south falls in zone-limited hazard zone-2.

 However, there are many areas in the capital Delhi which can be as dangerous as Zone-5.

 

 Losses during an earthquake mainly depend on the following factors.

 Vibration power: The vibration power of an earthquake decreases with distance.  During an earthquake, the intensity of intense vibration along the fault section is halved in 13 km distance, one quarter in 27 km, eighth part in 48 km and sixteenth in 80 km during its glide or slippage.

 Vibration Length: The length of the vibration depends on the rupture of the fault during the earthquake.  Prolonged shaking of buildings causes more and permanent damage.

 Type of soil: Tremor is very high in fine, fine and wet soil.

 Type of building: Some buildings are not safe enough from vibration during earthquake.