Question

explain the mechanism of an earthquake

Answer 1

The focal mechanism of an earthquakedescribes the deformation in the source region that generates the seismic waves. In the case of a fault-related event it refers to the orientation of the fault plane that slipped and the slip vector and is also known as a fault-plane solution. Focal mechanisms are derived from a solution of the moment tensor for the earthquake, which itself is estimated by an analysis of observed seismic waveforms. The focal mechanism can be derived from observing the pattern of "first motions", that is, whether the first arriving P waves break up or down. This method was used before waveforms were recorded and analysed digitally and this method is still used for earthquakes too small for easy moment tensor solution. Focal mechanisms are now mainly derived using semi-automatic analysis of the recorded waveforms.

Answer 2

The Earthquakes are caused by the movement of plates, which collectively from the earth's crust.

These plates are of various size, and they are very slowly but constantly drifting underneath the earth's surface.

When they collide or drag, the pressure causes those plates to distort.



Eventually the pressure reaches its limit causing the plates to jump or crack in order to release its energy.

This creates vibration at the surface, known as earthquake.