An earthquake can occur in an area and by some human intervention such as a mine collapse or a high power explosion. But this will bring about a low-intensity vibration.
Natural earthquakes occur due to factors related to the motion of the Earth’s matter.
The Earth consists of the inner core, the outer core, the mantle and the crust which is very close to its surface.
The crust is made up of huge plates called tectonics. These plates are constantly moving as the lava in the Earth’s mantle moves and pushes them. Their movement is infinitesimal.
An earthquake occurs when two plates come in contact with a huge force. Then there will be a breaking of a plate or riding or friction. This is the seismic vibration and lasts until the plates come to their new position.
The following figures help us better understand the phenomenon.
[Source: www.coolweb.gr]
