What causes Earthquake

What causes Earthquake

Posted by Manisha on March 19, 2020

The first time when I face the Earthquake, I was just 11 years old and don’t know much about this. I was wondering how this is possible and starts looking up for its reasons and causes. So here we will discuss its causes and related terminologies.

In simple words—The shaking of the surface of the earth or a part of it is known as Earthquake. Resulting from the sudden release of energy in the Earth’s lithosphere that creates seismic waves.

Terms related to Earthquake


TermDefination
SEISMOLOGYThe science which studies the earthquakes is called seismology.
SEISMIC WAVESThe waves of energy caused by the earthquake, inside the earth are called seismic waves.
FOCUSThe point (inside the earth) where earthquakes are generated first is called focus or HYPOCENTRE.
MAGNITUDE OF EARTHQUAKEIt is a measure of amount of energy released. It depends upon the Amplitude, Acceleration and Frequency.
SHOCKDue to earthquake, when earth tremor or temblor is known as shock.
ISOSEISMAL LINEThe line which connects the points having same earthquake intensity, on the surface of earth is called ISOSEISMAL LINE.
HOMOSEISMAL LINEIt is a line which joins the places which experience the earthquakes at the same time.
EPICENTREThe point on the surface of earth, where seismic waves reach first is known as epicentre.

Causes of Earthquake

1.Volcanic Eruption

The volcano prone areas or after a volcanic eruption nearby areas face earthquakes. Sometimes when the magma is unable to come out on the surface of the earth due to hard rocks then it Keeps on trying, In this case, pressure increases results as an earthquake.

2.Folds and Faults

Faults and folds in between he rocks cause tremor results earthquakes e.g 1934 Bihar earthquake, 1950 Assam,1991 Uttarkashi earthquake.

Contraction of Earth— Our earth is contracting every year from its birth due to cooling, which indirectly leads to the earthquake.

3.Isostasy

It is the state of gravitational equilibrium between the earth’s crust and mantle. Crust floats at an elevation that depends on its thickness and density. And whenever rocks try to balance in between then an earthquake occurs. e.g. 1949 Lahore earthquake.

4.Plate Techtonics

Our earth's surface is divided into many big and small plates. These plates keep on moving due to high pressure and conventional currents, inside the earth, which leads to the earthquake. —— Circum Pacific ring of fire is a great example of plate boundary earthquake areas.

5.Elastic Rebound Theory

Given by Dr.S.F.REED. According to this theory, the interior rocks are flexible like rubber. Whenever pressure increases on these rocks due to extreme energy, pressure etc.rocks broke down into different pieces and starts moving in the opposite direction which leads to the Earthquake on the earth’s surface.

6.Artificial Earthquake

This earthquake happens due to human activities. For example, Bom defusion due to the collapse of mine roofs.

7.Other Causes

Dams, Avalanches, and Mines. These also cause earthquakes but of lower intensity.

The intensity and magnitude of an earthquake can be measured by the RICHTER SCALE which is invented by Charles F.Richter in 1935. Then in 1965 BENO GUTENBERG modified this into LOGARITHMIC SCALE.