(redirected from Earthquake foci)
Also found in: Encyclopedia.


The surface position directly beneath the center of a nuclear explosion.

hy′po·cen′tral (-sĕn′trəl) adj.


(ˈfoʊ kəs)

n., pl. -cus•es, -ci (-sī, -kī), n.
1. a central point, as of attention or activity.
2. a point at which rays of light, heat, or other radiation meet after being refracted or reflected.
a. the focal point of a lens.
b. the focal length of a lens.
c. the clear and sharply defined condition of an image.
d. the position of a viewed object or the adjustment of an optical device necessary to produce a clear image: out of focus.
4. (of a conic section) a point having the property that the distances from any point on a curve to it and to a fixed line have a constant ratio for all points on the curve.
5. the point of origin of an earthquake.
6. the primary center from which a disease develops or in which it localizes.
7. to bring to a focus or into focus: to focus the lens of a camera.
8. to concentrate: to focus one's thoughts.
9. to become focused.
[1635–45; < Latin: fireplace, hearth]
fo′cus•a•ble, adj.
Mentioned in ?
References in periodicals archive ?
Recent activity of the area is confirmed by recent frequent occurences of earthquake foci, but also by height changes evaluated from repeated measurements on the 1st order lines of the State Leveling Network.
There is a dense cluster of earthquake foci with magnitudes (M) from 1 to 3M surrounding the Boskovice town.
Figure (4) is a location map of the earthquake foci that located in the Upper Egypt during the period from 1981-2006.

Full browser ?