1. An area within a known active earthquake zone within which no significant earthquakes have been recorded. It is not always clear whether this gap represents a zone where gradual motion takes place continually so there is no strain accumulation, or where motion is locked and strain is accumulating.

2. (shotpoint gap) In split-spread seismic reflection shooting, the distance between the shot point and the nearest groups of geophones, which is larger than that between subsequent geophone groups at larger offsets.

3. (inter-record gap) A blank space on a magnetic tape which signals the end of one block of seismic data (one seismic record) and heralds the start of another. It is used to facilitate the transfer of magnetically recorded data into a computer system.