Here's why:

* Tectonic Plates: Earth's outer layer (lithosphere) is made up of large, moving plates called tectonic plates.

* Faults: These plates are constantly interacting along boundaries called faults. These are zones of weakness in the Earth's crust.

* Forces: The movement of these plates is driven by forces within the Earth's mantle. This movement can be either:

* Convergent: Plates pushing towards each other.

* Divergent: Plates moving apart.

* Transform: Plates sliding past each other.

* Earthquakes: The pressure built up from these forces along faults eventually causes the rocks to break and slip. This sudden release of energy is what we experience as an earthquake.

In summary: Earthquakes are a direct result of the forces pushing and pulling tectonic plates along faults in the Earth's lithosphere.