MEANING, CAUSE , AND MEASURING SCALE OF EARTHQUAKES

By Idongesit F. Oduok

What is earthquake

Earthquake is defined as any sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks.

 

What causes earthquake

An earthquake is caused by a sudden slip on a fault. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel.

 

How is earthquake measured

The Richter scale also called the Richter magnitude scale or Richter's magnitude scale is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 paper, where he called it the "magnitude scale".

 

The scale is graded from 0 – 9. Earthquake measuring 0 – 4 are minor, from 4 – 7 are moderate, and over 7 are severe.

 

Focus of earthquake

The focus is the place inside Earth’s crust where an earthquake originates. The point on the Earth’s surface directly above the focus is the epicenter. When energy is released at the focus, seismic waves travel outward from that point in all directions. There are different types of seismic waves, each one traveling at varying speeds and motions. It's these waves that you feel during an earthquake.

 

Effects of earthquake

1.    Earthquakes cause the death of people and animals in places where they occur.

2.   They also cause the destruction of buildings, roads, bridges, railways and telecommunications.

3.    They also displace parts of the earth’s crust, either vertically or laterally.

4.    They can also raise or lower coastal rocks.

5.    They can raise or lower parts of the ocean floor.

They can cause landslides and open deep cracks in surface rocks.