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Transform Plate Boundaries

Plates sliding past each other create transform faults.

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San Andreas Fault

San Andreas Fault


Credit: Kate Barton, David Howell, and Joe Vigil
Source: http://en.wikipedia.org/wiki/File:Sanandreas.jpg
License: CC BY-NC 3.0

The San Andreas Fault goes up from Mexico through western California and offshore in northern California. This transform fault separates the Pacific Plate on the west with the North American Plate on the east.

Why It Matters

  • The San Andreas Fault is one of the few places on land where two plates are in such close contact.
  • The San Andreas Fault and its branches have 10,000 quakes a year.
  • The Farallon Plate subducted and became two smaller plates, creating the San Andreas fault.
  • Credit: USGS
    Source: http://en.wikipedia.org/wiki/File:San_Andreas_Fault_Sequential_Diagrams.jpg
    License: CC BY-NC 3.0

    Plate-tectonic evolution of the San Andreas fault [Figure2]


Explore More

With the links below, learn more about the San Andreas Fault. Then answer the following questions.

  1. What type of fault is the San Andreas? How are the pieces of crust on each side of the fault moving?
  2. Why are earthquakes on the San Andreas Fault so large in some locations?
  3. Why is Baja California splitting away from mainland Mexico?
  4. Describe how the San Andreas Fault forms as seen in the Tectonic History of Western North America video.

Image Attributions

  1. [1]^ Credit: Kate Barton, David Howell, and Joe Vigil; Source: http://en.wikipedia.org/wiki/File:Sanandreas.jpg; License: CC BY-NC 3.0
  2. [2]^ Credit: USGS; Source: http://en.wikipedia.org/wiki/File:San_Andreas_Fault_Sequential_Diagrams.jpg; License: CC BY-NC 3.0


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