Fault separation is the distance between displaced parts of a marker horizon, measured along a specified line. Separation will vary depending upon the line chosen.

Dip separation or vertical separation is the offset distance measured parallel to the dip of the fault. Heave is the horizontal component of the dip separation and throw is the vertical component of the dip separation (Figure 1).

Figure 1. Illustration showing dip separation, heave, as well as throw. By K.P. Hefferan, available from http://www.uwsp.edu/geo/faculty/hefferan/geol320/faults.html.

Strike separation or horizontal separation is the offset measured parallel to the strike of the fault.

Net slip and separation are the same if the line along which separation is measured parallels the net slip.