The epicenter of an earthquake is the point on Earth's surface vertically above the hypocenter, the place where the rupture originates. It is therefore the place on the surface that is closest to the seismic focus. The potential damage usually, but not always, increases approaching the epicenter. Larger events where the rupture spreads over a long distance, the damage can be equal or higher to the damage near the epicenter at any point above the rupture.
The epicenter is usually calculated by triangulation of epicentral distances (Δ) measured with at least three seismographs by measuring the time difference between the arrivals of P-waves and S-waves.