Earthquake is one of those natural calamities that can be predictable yet inevitable. We all are familiar with the word earthquake and relate it to the condition when the earth starts shaking and vibrating. What is the basic cause of an earthquake? Volcanic activities that are frequent; and the movement of tectonic plates under the crust of the Earth is the reason behind the occurrence of earthquakes.

Let us find out more about the types and some more reasons of earthquake.

The first thing to know is that the Earth's crust is made up of solid core, molten magma mantle and the tectonic plates. All this constitutes the Earth's crust. These plates are moving continuously because of the convection currents of the molten lava in the deep layers of the Earth. This results in either the plates sliding against one another, or moving away from one another. Well, all such massive movements inside the Earth's crust are felt by the living organisms, including humans. Mountains and the valleys have been formed due to this continuous movement below the Earth's crust. There is a meeting point which is basically a point of friction between two plates. This meeting point, in geological terminology, is referred to as earthquake fault line. Sometimes these are also referred to as fractures on the Earth's crust. Once the plates start moving, the potential energy, also referred to as the stored energy, is let loose from the point of intersection, called hypocenter. This results in earthquakes.

Earthquake occurs in three waves. These waves are namely P-waves, the high frequency short length longitudinal waves; S-waves, the secondary high frequency, short length transverse wave; and the L-waves, the low frequency, long wavelength transverse waves.

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