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4.6: Transform Boundaries

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    Transform Boundaries

    Transform boundaries are locations where one plate is sliding past another.
    • Can occur in any crustal type (OC or CC)
    • Crust is neither produced or destroyed

    Continental Transform Faults

    • In continental crust, transform faults can be large destructive faults like the San Andreas Fault System in California (Figure 4.19).
    • Earthquake magnitudes up to 8.5 have been measured.
    • Rates on the San Andreas Fault (SAF) average 2-5 cm/yr or LA will be adjacent to SF in about 20 million years!
    • Compression(and uplift) or tension (and down-warping) can occur. The high mountains in Southern California are a result of this kind of compression along the SAF including the San Gabriels, San Jacinto, and San Gorgonio Mountains.

    Oceanic Transform Faults
    • In ocean crust, smaller transform faults occur perpendicular to the spreading centers.
    • They have smaller earthquakes associated with them, when compared with their continental cousins.
    • These faults occur where there is a bend or change in the rate of spreading along the MOR.

    Western North America Plate boundary
    Figure 4.19. The San Andreas Fault system is part of a complex transform plate boundary along the West Coast of North America.

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