Geophysical migration is the process by which geophysical events (changes in energy) 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 an 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. The end result is that the migrated image typically resolves these areas of complex geology much better than non-migrated images. Consequently, a form of migration is one of the standard data processing techniques for certain geophysical methods (seismic and ground penetrating radar). Computational migration needed for large datasets acquired today is extremely demanding on modern computers and is the subject of intense research, both within the geophysical industry as well as academic circles.
Need for Migration
Seismic waves are elastic waves that travel through the Earth with a finite velocity, which is governed by the material properties of the rocks. When the waves reach a rock unit with a different velocity some of the seismic energy is either absorbed, transmitted to the next layer, or reflected back towards the surface by the reflector (new rock layer). The reflected energy from these velocity contrasts arrive at the surface, and are recorded by Geophones that are placed at certain location away from... Read More