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.

Synonyms: offset well

See: 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