Geologists describe the way a fault moves in terms of the direction of the slip. A strike slip fault describes when the plates strike one another, then slip in a horizontal motion that is parallel to the struck surfaces. A strike slip fault is most common along a transform boundary, but occasionally has been seen to occur along other boundaries areas as well. Most of the transform boundary zones occur along the ocean floor. There are a notable few that can be found on the land, such as the San Andreas fault zone in California. These are both “deep seated” types of transform boundaries, which are located on interplate boundary zones. There are also strike slip faults that occur intraplate. They are referred to as “thin-skinned”, and confined to the crust. An example of this is faults along continent-continent blocks where the continents move with respect to one another due to a convergent zone.
Like all faults, the strike slip fault is driven by plate movements. Plate movements, in turn, are powered by magma as it circulates within the earth. It has long been known that plates move at different rates over different times. It has recently been noted that the width of the subduction zone that is nearest the plate. The smaller width of the subduction zone is, the less mass there is to push the plate edge down into the depths of the earth, and the slower the plate moves.
There are other interesting features that form along a transform boundary. There is are striking features that are elongated lakes called sag ponds that form when the land around the strike slip fault crumbles and settles. Another common feature along strike slip faults are shutter ridges, which form when the rock ridge is shifted and blocks a stream or river, and its counterpart to the offset stream.
Research is still ongoing along many strike slip faults. In the last 10 years, more impacts of strike slips faults have been noted. Interestingly, volcano instability has been noted. The volcano becomes unstable as a direct result of the shifting that happens along the transform boundary and strike slip faults. Not only does the volcano cone start shifting and falling apart on the surface, but the magma that feeds the volcano is unable to do so. The magma must find a new place to push up and form a new volcano elsewhere. These collapses are called “extensional structures” as a general term, and go through an inflation-deflation process that is caused by the magma swelling and retreating inside of the collapsed chamber.
Research into the role of the strike slip fault is still ongoing. With each new model and discovery, the view on how they interact with plate tectonics broadens and deepens. As the data is changing the understanding of strike slip faults, so too, does the understanding of the dynamics of each fault system.
