Earthquakes generally occur as a result of rock slippage along a fault in the Earth’s crust. The exact point where this slippage occurs is known as the hypocenter (also known as the focus). Seismic waves radiate energy out in all directions from the hypocenter. This transfer of energy is very similar to what happens when you drop a rock in a still pond. The point on the Earth’s surface directly above the hypocenter is known as the epicenter.

Animation illustrating the relationship between the hypocenter and the epicenter.