TERMINOLOGY
1. Focus: The point on the fault where slip begins is the focus. It is also called as hypocentre
2. Epicentre: The point vertically above the focus on the surface of the earth is called epicentre.
3. Focal Depth: The depth of focus from the epicentre is the focal depth.
4. Epicentral Distance: Distance from epicentre to any specific point of interest on the surface of earth is epicentral distance.