Earthquake – All about

Earthquake can be called a Natural calamity because it results in a lot of Human and property loss. Earthquake is caused due to the continuous shifting below the surface of the earth both under land and the sea. In fact it is learnt that the present continents got their geographic locations because of massive earthquakes and volcanoes which occurred millions of years ago.

There is constant movement of the plates under the earth’s crust because of the intense energy that lies beneath. And this movement of plates results in an earthquake at faults on the earth’s crust. A fault is the weak part of the earth which tends to break or move due to pressure. An earthquake is measured with a seismograph and the measurement is recorded on Richter scale. However, the movement and the disturbance of the earth is measured by Mercalli Scale (developed by Giuseppe Mercalli, an Italian Volcanologist between 1883 and 1902).

There are three categories or faults of earth quakes namely, strike slip, dip slip and normal.
Strike slip earthquake is one where the land plates strike and slip horizontally causing the earth to move sideways or say left to right or vice versa.
Normal and reverse fault causes vertical movement of land.

Earthquake also occurs due to volcanic activity. The movement of massive lava from beneath the earth’s surface causes the movement of the earth so that the magma tears and passes through towards the surface of the earth. This immense movement of the magma causes earthquakes too.

Earthquakes occurring beneath the sea can cause major hazards like the Tsunami.

After shock means smaller earthquakes at the same fault where the main shock has already taken place in the recent past. The main shock leaves some gaps under the surface of the earth and the crust tries to adjust in these gaps causing after shocks.

Linus Orakles
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