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AbhimanyuVishwakarma
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Earthquake is one of the dangerous and life threatening natural disaster which can come anytime and anywhere on the earth. Most of the earthquakes come with minor tremors however larger earthquakes with strong tremors generally begins with slight tremors but soon gets changed into more violent shocks. Stronger earthquakes generally end up with huge and forced vibrations at long distance from the main point of arousal. It gradually diminishes with reduced aftershocks. The focus of earthquakes becomes the subterranean point where it originates. Magnitude and intensity of the earthquake can be measured with the help of variety of scales such as Richter scale, moment magnitude scale, modified Mercalli scale, etc. Earthquake is a life threatening event that responsible for the huge damage to the living and non-living beings. Earlier, it was quite hard to imagine the intensity of the earthquake before its occurrence. However, now-a-days, it has become easy to estimate the magnitude and intensity of earthquake because of the instrumental advancement in the world. People, in the ancient time, believed that earthquake occurs as mother earth was angry with them. It was Aristotle (a great Greek philosopher) who relate the occurrence of earthquake to some physical factors. According to him, the compression of air within the arch escapes cause shakes of some part of the earth surface and called as volcanic activity. Large earthquakes may destroy things to a great extent as they take down huge buildings, cause injury and thus death of people. There are various scales used to measure the intensity of shaking and the magnitude of an earthquake. The scale showing magnitude 3 or less indicates that the earthquake is less harmful however the scale showing magnitude 7 or more causes huge level damage over a wide range of area. Earthquake which occur under the ocean take the form of a tsunami. It is a giant form which can cause death and destruction to the living and non-living things. High intensity earthquakes give rise to the landslides in the surrounding areas. In the ancient time, people in China were used a device in order to guess the occurrence of earthquake. The device was similar to the jar having dragons on top and surrounded by frogs with open mouths. They guess the occurrence of earthquake by the exchange of fitted ball in dragon's mouth to the frog's mouth. The direction of earthquake was decided by the position of frog receiving a ball. This device was an effective tool in the ancient time to figure out the origin of an earthquake. Causes of Earthquake One of the main reasons of the earthquake is plate tectonics which causes tectonic movements in the earth surface. Tectonic plates under the earth surface collide to each other and ride over the other which becomes the reason of mountain formation, earthquakes and volcanoes.