Earthquakes occur when the ground is subjected to so much force that it fractures or breaks. Scientists can explain how most earthquakes are caused using simplified theories of the Earth's structure.
In ancient times earthquakes were thought to be caused by restless gods or giant creatures slumbering beneath the Earth.
The process of ground being subjected to a growing force until it snaps or breaks is explained in a theory called the elastic rebound theory.
Tectonic plates can move relative to each in different ways. This movement gives rise to different types of plate boundaries with different properties and characteristic earthquakes.
There are a number of competing theories that attempt to explain what drives the movement of tectonic plates.
Studying the signals from distant earthquakes has allowed scientists to determine the internal structure of the earth.
Earthquakes do not occur randomly on the Earth. The pattern of earthquake locations can be explained by assuming the Earth's surface is made up from rigid plates that are in motion relative to each other.