Cause of Earthquake

Earthquakes are caused due to disturbance in the earth’s crust. On earth, there are different continents. Each continent sits on hard layer called crust. Crust is divided into different fragments called plates. These plates sits on the layer called mantle. Plates sitting on the mantle moves continuously. When plates slide past each other then their rough boundaries rub over each other. However if rubbing is so intense then it can be felt at surface in form of earthquakes. In other situation, due to collision one plate goes under the other again generating the shock at the surface.



It results into rising of one surface relative to other again generating the shock at the surface. It results into rising of one surface relative to another. As reason behind the earthquake is known, it is not yet possible to predict when and where the next earthquake will occur. Other reasons of earthquake includes volcano eruptions, or if a meteor hits the earth, or an underground nuclear explosion.

Seismic Waves

Earthquake produce waves on the earth surface. These waves are called seismic waves. However, there is an instrument used to record seismic waves called seismograph. The instrument is a vibrating rod or pendulum. It vibrates when an earthquake occurs. Moreover a pen is attached to the vibrating system. The pen records the seismic wave on paper moving under it. Using this seismograph, scientist construct the map of earthquake and also estimate the power of earthquake. Moreover, the power of earthquake is expressed in terms of magnitude on Richter scale. Really destructive earthquakes have magnitude higher than 7 on Richter scale.

Seismic Zones

Earthquakes are caused due to movements of plates, therefore, boundaries of the plates are weak zones. In weak zones chances of earthquakes are maximum. These weak zones are also known as seismic or fault zones.

Protection against Earthquake

• People living in seismic zones must be specially prepared. Buildings in these zones must be designed in such a way that they can withstand major tremors. By consulting qualified architects and structural engineer, buildings must be constructed quake safe. However in highly seismic area use of mud or timber is better choice than heavy construction material. Roof must be light enough, such that even if earthquake occurs then falling of roof will not cause much damage



• If cupboards and shelves placed near the walls then they will not fall easily. Moreover, the places of hanging wall clocks, photo frames, must be chosen such that during earthquake these won’t fall on people. All buildings especially tall buildings must have fire fighting equipment so as to tackle the issue of fire.

Safety measures when earthquake strikes

• At home
1. Take shelter under a table and stay there till shaking stops.
2. Stay away from tall and heavy objects that may fall on you.
3. If you are in bed, do not get up. Protect your head with a pillow.
• Outdoors
1. Find a clear spot, safe from buildings, trees and overhead power lines. And drop to the ground.
2. If you are in a car or a bus, do not come out. Ask the driver to drive slowly to a clear spot. Do not come out till the tremors stop.

Keywords: Seismic waves, Seismic zones, Richter scale, Mantle