Transform Fault - Transform Fault Types

Transform Fault Types

In his groundbreaking work on transform fault systems, Tuzo Wilson said that transform faults must be connected to other faults or tectonic plate boundaries on both ends; because of that requirement, transform faults can grow in length, keep a constant length, or decrease in length. These length changes are dependant on which type of faults or tectonic structures connect with the transform fault. With this in mind, Wilson described six types of transform faults:

Growing length faults: In situations where a transform fault links together a spreading center and the upper block of a subduction zone or when two upper blocks of subduction zones are linked the transform fault itself will grow in length.

Constant length faults: In other cases, transform faults will remain at a constant length. This consistency can be attributed to many different reasons. In the case of a ridge-to-ridge transforms, it is caused by the continuous growth by both ridges outward, canceling any change in length. The opposite occurs when a ridge linked to a subducting plate, where all the lithosphere (new sea floor) being created by the ridge is being subducted, or swallowed up, by the subduction zone. Finally, when two upper subduction plates are linked there is no change in length. This is due to the plates moving parallel with each other and no new lithosphere is being created to change that length.

Decreasing length faults: In rare cases, transform faults can shrink in length. These occur when two descending subduction plates are linked by a transform fault. In time as the plates are subducted, the transform fault will decrease in length until the transform fault disappears completely, leaving only two subduction zones facing in opposite directions.