4.6: Transform Boundaries

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Miracosta Oceanography 101
Miracosta)

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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.