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Q:1- Explain the internal structure of the earth with special references to earthquake waves?(20 marks)

Ans:

Introduction:
We have not been into the earth so far. But the geologists have discovered and assumed the internal structure of the earth with the help of seismic waves and have the earth have been divided into layers. The waves which can be measured in accordance with the scientific trend. However, while the earth quake waves at certain direction the scientific measurement can be done exclusively. Thus, it is the concrete evidence which explain the internal structure of earth i.e in solid inner core, liquid upper core, mantle and upper mantle respectively with the help of seismic waves.

Internal structure of Earth with the help of Seismic Waves
However, it is said in the introduction that the internal structure of earth can be justified with the assistance of earth quake or seismic waves. Thus, these waves are mainly two sort of waves.

L-Waves:
L-waves or longitude waves which use to travel along the surface of the earth.

Body Waves
Whereas body waves are of two sort i.e. P and S waves:

P-Waves:
P-Waves are called the Push waves or also primary waves. And the function of these waves are to shake the earth and these waves usually travel along the direction and destruct the earth's environment. Moreover, these sort of waves get their movement in the form of liquid.

S-Waves:
S-Waves are called shear waves prominently. These waves have an outstanding importance owing to the justification of the liquid into the earth exclusively while earth quake take place. These are the waves which are considered dangerously while the intensity goes to the immense shaking. Besides, these waves do not move into the form of liquid forms.

Internal Structure of the Earth
After getting in touch with the studies of seismic waves it can be discussed that there are four sort of layers of the earth.

1- Solid Inner Core:
It is the most inner core of the earth. Which is very hurt. Some times it get hot like the Sun. Moreover, according to the study of seismology that its size is nearly 70% of the moon. Besides, it is made up of iron–nickel alloy.

2. Liquid Outer Core:
Although it is hotter layer of the earth, less then the inner core. However, the thickness of liquid outer core is 2500 km & its outer layer is 2900 km below the sea level. Moreover, it contains the hotter liquid lava as well.

3. Lower Mantle (Solid):
Respectivly, it is on above the liquid outer core. Its thickness is about 2230 km. Besides it is extremly solved and contains oxides of MG, Iron and Si.

4. Upper Mantle
This layer of the earth is to be considerved partially molten. It extend from the base of the crust to 670 km below the surface. The zone of the upper mantle just bellows the crust is solid. It contains pores through which lawa comes onto the surface.

The Crust:
It is the outer layer of the earth. Moreover, it is very thin about between 0-60 km. However, it is the solid layer where we use to live exclusively.

In connection with the crust, the Continental crust is the most important that contains two types which are give bellow:

1-Continental crust

2-Ocean Crust


Conclusion:
With the help of seismic waves or earth quake waves, It can be said that the internal structure of the earth is dived into four layers. Moreover, the study of seismography gives the clear notion about the earth that it is the immensely hottest while we dug the earth going thoroughly crust to inner core respectively. As a matter of fact no one has gone into the earths inner core owing to extensive hottest temperature. Besides, the earth quake waves have an astonishing importance in this regard also in other regard while earth quake takes place. It is the seismograph which gives the calculation of intensity of an earth.