在地震学中，震源（hypocenter）是地震发生的起始位置，断层开始破裂的地方，震源向上投影到地表即为震央。利用地震波，可以决定震源。 依照震源的深度可将地震分为浅层地震、中层地震和深层地震。

The hypocenter (literally: 'below the center' from the Greek: ὑπόκεντρον) refers to the site of an earthquake or a surface or subsurface nuclear explosion. It is a synonym of the focus. (Confusingly, for a nuclear airburst the term hypocenter is a synonym for ground zero.)