The epicenter or epicentre (ancient Greek: επίκεντρον) is the point on the Earth's surface that is directly above the point where an earthquake or other underground explosion originates. The epicenter is directly above the hypocenter, the actual location of the energy release inside the earth. Seismic waves propagate spherically out from the hypocenter. Seismic shadowing occurs on the opposite side of the Earth from the earthquake epicenter because the liquid outer core absorbs the transverse or shear waves (S-waves ), and refracts the longitudinal or compressional (P-waves).

The term epicenter is also applicable to the center of other catastrophic events, such as an impact of a meteorite or comet. Colloquially, "epicenter" is used as a synonym for "center."