The hypocenter or hypocentre (literally: 'below the center' from the Greek υπόκεντρον), also known as the focus, is the location inside the Earth where an earthquake originates. It is directly below the epicenter at a depth known as the focal depth.

The term hypocenter also refers to the point on the surface of the earth directly below the air burst of a nuclear detonation. In this context, the term "ground zero" is synonymous with hypocenter.

The location of an earthquake's origin is determined by measurements based on seismic wave phenomena. As with all wave phenomena in physics, there is an uncertainty in such measurements that grows with the wavelength under consideration.

This is important, because very strong earthquakes radiate a large fraction of their released energy in seismic waves with very long wavelengths. The depth of the source of these waves is difficult to determine exactly.

Seismology

Hipokreizenn | Hypocentrum | Hypocenter | Hypozentrum | Hüpotsenter | Hipocentro | Subcentro (tertremo) | Hypocentre | Hipocentro | Pusat gempa | Ipocentro | Hypocentrum | Hyposenter | Hipocentro | Гипоцентр | Hypocentrum | Гіпоцентр