Before discussing What is cause of Earthquake? and Effects of Earthquake? you have to understand somewhat about the earthquake. So, let’s know it one by one clearly.
The word Earthquake is self explaining-the Earth-quakes that means the earth shakes and we feel the vibrations caused by these motions. Earthquakes are caused due to many reasons (later explained) but most commonly the term ‘Earthquake’ is used when shaking of the earth’s surface is caused due to some disturbances occurring inside the earth.
Whenever the earth is disturbed, vibrations are produced. The vibration produced by disturbance propagated in all directions from the place of origin.
Wherever these vibrations travel, an earthquake is said to have taken place. These vibrations are more intense near their source.
Earthquake slowly becomes feeble and begins to die as the distance from origin increases continuously. At a certain distance, it dies out. It is estimated that more than 10,000 large and small earthquakes occur every year.
But most of them are not of great concern for civil engineers, only a few of them, having high intensity, is a cause of major concern. Some earthquakes can be very destructive and result in the collapse of the structures, thus, resulting in heavy loss of life and damage to the buildings. Thus, it is necessary to study the earthquakes in detail and take every precautionary measure and protection, to minimize the loss of life and property.
Since earthquakes are unpreventable and unpredictable, so we should design the structures earthquake resistant which means that they should withstand earthquake forces without much damage thus loss of life and property is minimized.
An earthquake can be defined as the shaking of the earth’s surface due to any reason which, results in the release of a large amount of energy. The energy released during an earthquake is enormous.
For example, the energy released during the Bhui earthquake (India 200) was about 400 times more than the energy released by the 1945 atom bomb dropped in Hiroshima. The word seism means earthquakes.
Hence, The branch of science which deals with the study of earthquakes is known as seismology.
It includes causes and types of earthquakes, the study of the origin, propagation, recording and analyzing seismic waves. Earthquakes are a major cause of concern for civil engineers because the effect of this disaster is measured in terms of the extent of the damage.
This damage includes loss of lives and property both. Somebody has rightly said that “Earthquakes do not kill people but it is the structures built by them that do so.” Thus it is very necessary to make the structures earthquake resistant. So, the study of earthquake engineering is important for civil engineers to equip them with the basic knowledge of earthquakes, its effect on structures and various principles and techniques to be followed while designing and constructing earthquake-resistant structures.
In brief, the study of seismology or earthquake engineering is important because :
(i) It helps us in understanding the earthquakes, their nature, and effect on our life.
(ii), It helps us in designing and building earthquake resistant structures to minimize the loss of lives and property.
(iii) It also helps us in planning an effective disaster management program during an earthquake by preparing ourselves in a better way to reduce the effects of an earthquake.
What is cause of Earthquake?
Cause of Earthquakes is primarily due to two reasons :
(a) Volcanic causes
(b) Tectonic causes
2) Artificial disturbances
1) Natural Disturbances :
The natural disturbances which cause earthquakes are followed:-
(a) Volcanic Causes: Volcanic activity keeps on taking place in several parts of the world. Very often, it produces sudden outburst or explosions.
This impact is sometimes strong enough to produce vibrations in the nearby areas. People, living in Japan and Italy, have experienced this type of earthquake frequently. These earthquakes are not very deep and of mild intensity. The damage caused due to this type of earthquake is confined within a few kilometers. All volcanic eruptions don’t produce an earthquake.
(b) Tectonic Causes: Tectonic causes are those which occur inside the earth. According to the theory of plate tectonics, the Crust (Outermost layer of Earth) is made up of rocks and is divided into many plates.
These plates are constantly in motion in different directions and at different speeds. These rocks or plates have strain energy stored in them. The sudden slip at the fault (A sudden movement along a fracture or crack in the rocks) results in the release of strain energy in the form of seismic waves which causes the shaking of the earth.
The earthquake which occurs due to the sudden release of strain energy as a result of a sudden slip of fault is called a tectonic earthquake. This slip may occur along the preexisting crack/ fault or along a new fault plane. The magnitude of these earthquakes depends upon the amount of energy released. More than 90% of total earthquakes are because of tectonic reasons. Bhuj (2001) and Latur (1993) were tectonic earthquakes.
2) Artificial Disturbances :
Sometimes the surface of the earth vibrates due to man-made or artificial disturbance. These vibrations are very mild and affect the surrounding area only. The earthquakes of mild intensity are caused due to these external man-made agencies. Some of the artificial disturbances causing earthquakes are listed below:
(i) Nuclear tests and explosions.
(ii) Mining blasts in the mining area.
(iii) A massive landslide along hill slopes caused because of deforestation.
(iv) Large and deep excavations.
(v) Vibrations induced due to heavy machinery used in industries or movement of heavy vehicles. The vibrations or shaking caused due to the above reasons is very minor and limited to small areas only. All these causes occur over the earth’s surface so these are also called surface causes.
Effects of Earthquake
- Loss of Lives and Property
- Ground Shaking
- Surface Fault
So, i hope you liked this article on “What is cause of Earthquake | Effects of Earthquake” and remains helpful for you.