The point at which a fault first ruptures in the earth during an earthquake is called the

The hypocentre, or focus, is the underground point where a fault first ruptures during an earthquake.

The epicentre is the point on the surface directly above the hypocentre, not the rupture point itself.

Mouth is a volcanic vent term and has no meaning for the start of a fault rupture.

Since hypocentre names the rupture origin exactly, none of the above does not apply.

Seismic waves radiate outward in all directions from this focal point.

The depth of the hypocentre strongly influences how much shaking reaches the surface.