How does an earthquake begin?

Answer 1

Usually from slipping (faults and faulting) of tectonic plates or movement of fault planes, or when tectonic plates collide together. Oscillation by mechanical (man-made) means, explosions, landslides, rockfalls, and volcanic eruptions have been known to cause localized earthquakes. Underground (subsurface or near subsurface) detonations are a suspected additional cause of earthquakes.

Answer 2

An earthquake begins when stress along a fault in the Earth's crust causes the rocks on either side of the fault to shift and break, releasing stored energy in the form of seismic waves. This sudden release of energy creates vibrations that travel through the Earth's crust, leading to the shaking and ground movement associated with earthquakes.

Answer 3

Built up tension beneath the surface of the earth releases, like a rubber band contracting, and everything above surface is shaken.