(1) (n.) Geology. The horizontal displacement between points on either side of a fault, which can range from millimeters to kilometers. Perhaps the most readily visible examples of offset are features such as fences or roads that have been displaced by strike-slip faults, such as the San Andreas fault of California, USA. Syn: Offset WellSee: Fault, Strike-Slip Fault. (2) (N.) Geophysics. In surface seismic acquisition, the horizontal distance from source to receiver. in a vertical seismic profile, offset is the horizontal distance between the source and the wellhead or the surface projection of the receiver in the case of a deviated well. offset between seismic source and receiver creates a delay, or moveout, in the arrival time of a reflection that can be corrected before stacking and can be used to determine velocity. See: Acquisition, Arrival Time, Common-Offset, Extended Spread, Fold, Geophone Offset, Lithostratigraphic Inversion, Moveout, Mute, Normal Moveout, Perpendicular Offset, Shotpoint, Spread, Tail Mute, Two-Way Traveltime, Velocity Analysis, Vertical Seismic Profile, Walkaway Vertical Seismic Profile, Zero-Offset Data