The faults or transforming edges are those limits between tectonic plates in which there is a lateral displacement of one plate with respect to the other. These limits are neither constructive (as in ridges) nor destructive (as in trenches).
Two types of transform faults are distinguished:
- Those that cut the oceanic ridges, dividing them into short and straight segments, to adapt the ridge and the expansion of the ocean floor to the spherical geometry of the Earth.
- Those that constitute the passive edges between continental tectonic plates, which move laterally without producing or destroying lithosphere. For example, the San Andreas fault (California, USA).
Plate movement in transforming faults produces seismic movements of different magnitudes, such as:
- In the area of Gibraltar, the Eurasian and African plates are parallel, and move in the same direction, so the friction is not very great and the earthquakes are of low or medium intensity. For example, the earthquakes in Granada, Almería, Murcia, ...
- In the eastern part of the Mediterranean, the Eurasian plate and Africa are parallel, but their displacement is in the opposite direction, so that the earthquakes are of high intensity, as in Turkey.
- On the Pacific coast of North America, the contact between the Pacific and American plates is at right angles, and they form the San Andrés fault, in which high intensity earthquakes occur.