![]() ![]() The entire San Andreas fault system is more than 800 miles long and extends to depths of at least 10 miles within the Earth. The San Andreas is the "master" fault of an intricate fault network that cuts through rocks of the California coastal region. Wallace, USGS.)The Pacific Plate (on the west) moves northwestward relative to the North American Plate (on the east), causing earthquakes along the fault. This earthquake, however, was but one of many that have resulted from episodic displacement along the fault throughout its life of about 15-20 million years.Īerial view of the San Andreas fault slicing through the Carrizo Plain in the Temblor Range east of the city of San Luis Obispo. Several transform fault boundaries are involved.Ī sudden displacement along the fault on Approduced the great San Francisco earthquake and fire. The San Andreas fault is part of a complex structure of plate boundaries associated with the west coast of the United States. residents, the most famous example is the San Andreas fault in California. Neither production nor consumption of lithosphere occurs at these boundaries. Tectonic plates grind past each other at transform fault boundaries. The Piqiang Fault is a left-lateral fault.Transform Fault Boundaries Between Plates Transform Fault Boundaries Between Plates The unit of rock layers that moves toward the viewer relative to the red fault line is on the left. This method always works, no matter from which direction you are looking at the boundary!įigure 2.6.8. If it is on the left side, it is left-lateral. If the plate moving toward you is on the right side, the motion is right-lateral.Purple arrows show the direction the rock units (blue circles) are moving relative to a person looking down the red fault line. Based upon those displaced features, decide which rock unit appears to be moving toward you.Blue circles indicate distinctive rock units that have been displaced from one another by the fault. Find features that have been displaced apart from one another due to the sliding motion of the plates or rock units.įigure 2.6.6.The red color traces the fault line between rock units. Identify the boundary between the two rock units.įigure 2.6.5.To determine what type of transform fault it is, follow these steps: Google Earth imagery showing the transform Piqiang fault in China. For example, below is the Piqiang fault from China: Figure 2.6.4. How are these diagram different from the ones on Figure 2.6.2?Ī type of transform plate motion can be identified by examining the two tectonic plates from a bird’s-eye view. The different colors represent rock layers. Figure 2.6.3 Block diagram and horizontal view of a transform fault. Block diagram and horizontal view of a transform fault. Can you notice the difference? Figure 2.6.2. An examination of the two transform faults below demonstrates that they are very similar. However, these categories are not determined by the composition of the lithosphere. The motion at a transform fault is classified into two categories: right-lateral and left-lateral. Transform faults refer to the lateral displacement of large rock units due to the shearing motion caused by a transform boundary. Transform boundaries can cause both large faults and a series of smaller associated faults. Perhaps the most famous transform boundaries, however, are those on the continental lithosphere with effects that are directly felt by nearby cities and towns. Because the surrounding rock along the ridge is hard and brittle, it accommodates these shifts in spreading rates with sliding motions. They occur near these divergent boundaries because the spreading rate changes along a ridge. Most transform boundaries are associated with the spreading spreading centers at mid-ocean ridges. Although none of these events occur at transform boundaries, they are far from boring the continuous stress that builds within the lithosphere from the sliding motion causes faulting and earthquakes. No lithosphere is destroyed or created, and mountain chains are not built at transform boundaries. Shear stress operates at transform boundaries, which involves sliding motion. This motion does not create or destroy crust and will cause earthquakes, but no volcanoes.Ī transform boundary occurs when two tectonic plates move past one another. A transform boundary causes a fault between two plates of the lithosphere, which will slide past one another. ![]()
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