Short answer
The hypocenter, or focus, is the point underground where an earthquake rupture starts. The epicenter is the point on the surface directly above that start point. An epicenter is a map location; the hypocenter also has depth. 1 2
They locate the same earthquake in related but different positions: a subsurface origin and its surface projection.
On this page
At a glance
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| Question | Epicenter | Hypocenter |
|---|---|---|
| Position | On the surface | Inside Earth |
| Relation | Vertically above rupture origin | Rupture origin |
| Depth coordinate | Surface point | Needed to locate the point |
The table summarizes the cited definitions and the article’s stated scope. 1 2
What each thing is
Epicenter. The point at Earth’s surface directly above the place where an earthquake rupture begins. 1
Hypocenter. The point within Earth where an earthquake rupture begins; also called the focus. 2
Key differences
An earthquake begins at a location along a fault and rupture spreads from there. Maps frequently plot epicenters because they are easy to show in two dimensions, but that map symbol should not be mistaken for the full three-dimensional origin. 1 2
How to tell them apart
On a seismic report, look for latitude and longitude plus depth: the depth identifies the hypocenter. A surface map pin above it marks the epicenter. The two share horizontal coordinates by definition. 1 2
Where they overlap
Both refer to one seismic event and are used together in earthquake catalogs. Neither, by itself, gives the full extent of the ruptured fault or all places that shook strongly. 1 2
Edge cases
Large earthquakes rupture along long fault segments, so damage can extend far from the epicenter. Reported locations are estimates based on data and can be revised. “Focus” is another name for hypocenter. 1 2
Why the distinction exists
Seismologists need to distinguish where rupture begins in the Earth from the corresponding point on the ground that people can map. 1 2
Common misconceptions
The epicenter is not necessarily where shaking was strongest or where most damage occurred. It is directly above the hypocenter. 1 2
Examples
If rupture begins 15 kilometers below a town, that underground start is the hypocenter; the surface point directly above it is the epicenter. 1 2
Sources
Sources checked October 3, 2026.
- USGS — The Science of Earthquakes. Hypocenter and epicenter.
- USGS — Earthquake Hazards Glossary. Hypocenter/focus.