What causes an earthquake?

Earthquakes are caused by the sudden release of energy from the Earth’s crust, often due to the movement of tectonic plates. These plates are large sections of Earth’s outer shell that float on the semi-fluid mantle below. When the plates move—whether by sliding past, colliding, or pulling apart—stress builds up along faults. When the stress exceeds the strength of the surrounding rock, it results in an earthquake, sending seismic waves through the Earth. The magnitude of an earthquake depends on the amount of energy released during this process.