Earthquake is the vibration of the land or the back-and-forth movement of the land. Earth’s vibration is caused by waves of flexible compression passing through the earth’s crust. In other words, it can be said that an earthquake is a disturbance of the earth’s crust, due to which the earth starts moving and the earth’s crust starts moving back and forth.
When a part of the earth’s surface suddenly trembles as a result of some event happening inside the earth, it is called an earthquake. According to Barchester, “Earthquake is the vibration of the surface which arises in the short-term disturbance of the elastic or gravity equilibrium of the surface or the rocks below it.”
Earthquake waves propagate outwards from a center. The power of earthquake waves spreading from the center gradually decreases in all directions. It consists of several movements one after the other which gradually come to an end. In this, trees, upper parts of temples, and tall objects are known to move back and forth. In addition to undulating motions in earthquakes, subsidence of surface production is often found. The sound of thunder is also heard from the land and atmosphere.
Major Effects of Earthquake
1. Volcano- Whenever the eruption of a volcano is accompanied by an eruption, the areas near its mouth tremble and start shaking. In other words, it can be said that an earthquake occurs. Sometimes earthquakes occur in the regions of the volcano even when there is no eruption, due to which the attempt of the material of the earth’s womb to come out of its full force and the obstruction of the path of matter by the upper hard rocks.
2. Collapse of the Earth Many scholars believe that the temperature of the earth keeps on decreasing gradually. As the temperature decreases, the earth shrinks. The shrinking of the earth causes chaos in its layers and vibrations to occur in many parts of it, which is called an earthquake.
3. Theory of isotope-according to scientists, siel means the earth’s surface rocks which are descending on the geological rocks. When the rocks of the higher ground of the earth’s surface keep getting eroded and deposited in the lower parts by the means of erosion, the higher ground rises to maintain the balance of the earth and the lower ground gets pressed down because of the erosion of the higher ground. The load gradually decreases and due to the deposition, the weight of the low land gradually increases. As a result, there is a rise in the area of decrease in the load and a depression in the area of increase, due to which the equilibrium is maintained.
4. Fault Actions- When there is pressure from opposite directions in the upper crust of the earth’s surface, it bends, but when the surface crust is hard or when the strength of the pressure is high, cracks burst at the place of bend in the upper crust. . When a crack breaks, the rocks of the crust move up or down depending on the extent of the crack. With this action, vibration is generated in the nearby area. The specialty of the earthquakes thus generated is that even after the major shock of the earthquake, short-term shocks continue for some time because the rocks keep wheezing for a long time after breaking.
5. The best gases of the earth- When the water reaches the earth’s womb, it reaches the hot rocks and immediately turns into language and the steam tries to go out. Whenever this action happens at a fast speed, due to their pressure, the surface starts shaking and a terrible earthquake occurs.
6. Artificial Earthquakes – Artificial earthquakes are caused by human reactions. Such actions of man, which put a lot of pressure on the surface, are due to generate earthquakes. The Earth was shaken by the detonation of the atomic bomb in Hiroshima, Japan. Due to the running of trains, vibrations often arise on the surface of the railway route and in the bridges. Earthquakes are caused by the movement of snow bodies and rock blocks.
Type of Earthquake
There are many types of earthquakes, which are classified on different grounds. They are described below
1. based on the cause of origin The following two categories of earthquakes can be done based on the cause of origin–
(a) Artificial earthquake and (b) Natural earthquake
(a) Artificial Earthquakes – These include those earthquakes whose origin is due to humans. An earthquake caused by the disturbance caused by man-power is called an artificial earthquake. from a bomb blast
The generation of vibrations in the surface area is a typical example of this.
(b) Natural earthquake – If the disturbance causing the earthquake is caused by any natural causes then it is called a natural earthquake. These can again be divided into two parts
(i) Volcanic earthquakes – Under this, those earthquakes come due to the eruption of the volcano or the intrusive actions of the volcano. Similar earthquakes occur in Japan.
(ii) Earthquake Earthquakes – Under this, earthquakes arise as a result of the movements on the earth’s surface. Earthquakes occurring in India or other mountainous regions are of this type.
2. Earthquakes based on nature of the origin of movements
Earthquakes are also classified based on the nature of the origin of the movements. On this basis, there are two classes of earthquakes
(a) tectonic earthquake – movement in the earth’s surface There is a sudden push from the ocean or a push keeps on coming after some time and many wave motions or vibrations are generated one after the other on the adjacent rocks. This is how earthquakes originate. The only reason for causing movement in the earth’s surface is due to geological movements like ring and rift bursting.
(b) Volcanic earthquake – In a volcanic eruption, the geothermal fluid finds a way out. Naturally, there are shocks to the crust immediately before, during, and after the eruption. Hence, vibration is generated on the earth’s surface. These shocks are very intense and harmful. But it should be remembered that not all volcanic eruptions are earthquake-producing.
Earthquake belts are found in the areas of fold mountains and near the shores of the sea. There are two main boxes
1. Perimeter belt of the Pacific Ocean.
2. Middle Atlantic Ocean and Mediterranean Belt
The famous scientist Mantisas de Valor has discovered that earthquakes occur more in the outer direction of the mountains and where the slope is higher, but volcanoes are also found in the inner seaside of the mountains. Earthquakes are related to the standing temporary edges of newly folded mountains. The Bihar earthquake is an exception as it occurred in areas of low slopes.
About 40 percent of earthquakes occur in the first belt and 54 percent of the Pacific belt in the second belt surrounds the Pacific Ocean from the southern tip of the Andes to Alaska and from Kamswatka to New Zealand. Due to the combined action of stratification and volcanic eruption, severe earthquakes occur in this belt.
In the second belt, there is a mountain range from the Pyrenees to the Himalayas. Due to stratification in this belt, more earthquakes occur. Many parts of this belt are thousands of kilometers away from the volcano. One branch of this belt is spread over the mid-oceanic coast. Its most active part is at the equator. The second branch of the belt extends through the Jordan Valley to the rift valley of East Africa. One of its branches also goes to the Indian Ocean via the Aravana peninsula.
Effects of Earthquake
This is a natural phenomenon that makes the human heart tremble. The destructive effects on human beings are considered by it to be a curse. Earthquake causes both destructive and constructive work on the earth, but destructive work is more in quantity.
(1) destructive effect
(i) damage to things made by man
(ii) destruction of cities
(iii) outbreak of flood
(v) cracks in different parts
(vi) uplift and subsidence of land
(vii) origin of fire or fire
(viii) generation of water waves.
(2) Constructive beneficial effects of the earthquake
1. Earthquake causes landslide action which is helpful in weathering. If the fertile soil of any part reaches fertile land, it makes that area cultivable.
2. Due to earthquakes, there are sudden folds of rocks and faulting. Due to these, water sources are born which are beneficial for human beings.
3. Earthquake gives sudden rise to a site and creates a deep ocean in some, which later on are beneficial for humans as the natural landscape.
4. Large cracks occur in the surface due to earthquakes, due to which many minerals are easily mixed.
5. When the terrain becomes particularly bumpy due to an earthquake, then many addresses of the Earth’s womb can be easily seen clearly, which increases the knowledge of the internal structure of the Earth’s womb.