Seismic migration
![A zero-offset non-migrated data set. Raw zero-offset data for a simple syncline in a constant velocity world. Notice the signature bow-tie effect in the image. This is the result of reflections occurring from both sides of the syncline, and arriving at the same receiver at different times. Migration can correct this effect.](/Images/godic/202502/13/SimpleSyncline4828.jpg")
![A zero-offset migrated data set of the File:SimpleSyncline.jpg data. This data was migrated using a time-migration referred to as phase-shift which operates in the Fourier domain. The migration has replaced all events in their correct locations, successfully reconstructing a syncline. However, there are erroneous events (swinging arcs) throughout the image which are migration induced noise.](/Images/godic/202502/13/PhaseShiftMigSimpleSyncline4828.jpg")
![An example of simple graphical migration. Until the advent of modern computers in the 1960s and 1970s this was a method used by geophysicists to primitively 'migrate' their data. This method is obsolete with the advent of digital processors, but is useful for understanding the basic principle behind migration.](/Images/godic/202502/13/GraphicalMigration4828.jpg")
Seismic migration is the process by which seismic events are geometrically re-located in either space or time to the location the event occurred in the subsurface rather than the location that it was recorded at the surface, thereby creating a more accurate image of the subsurface. This process is necessary to overcome the limitations of geophysical methods imposed by areas of complex geology, such as: faults, salt bodies, folding, etc.