Faults, Plate Boundaries, & Stress—How are they related?

8min 43s Novice Spanish

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How 3 basic types of stress affect both faults and plate boundaries.

[updated 2021]

Earth-science educators, do you ever get asked, "What is stress? Why do faults form in Earth’s crust? or How are faults related to tectonic plate boundaries?"

This animation describes stress in Earth's outer layer and how it leads to faults and plate boundaries. Earth’s thin, brittle outer shell of rock is under a constant state of stress. Stress impacts the formation of small local faults, and broader tectonic plate boundaries. How the rock responds, depends on the type of stress and the conditions the rock is being subjected to when it encounters stress. It is this change in Earth’s crust that generates different types of faults and plate boundaries.

Timecodes
0:00 Intro
0:26 What IS stress?
1:03 Type of stress
1:50 Elastic deformation
3:20 Ductile deformation
4:04 Brittle deformation
5:52 Extensional stress
6:18 Compressional stress
6:59 Shear stress
8:01 Conclusion

Keypoints:

  • Stress acts on rock and can change its shape or volume
  • Rock responds to stress depending on pressure, temperature, or minerals
  • Rock deforms by three forms of deformation: elastic, ductile, brittle.
  • Direction of stress determines fault types: tension stretches, compression shortens, shearing pushes horizontally
  • fault types also relate to the three plate boundary types

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This clip includes selected excerpts from the animation, "Earthquake Faults, Plate Boundaries, & Stress".

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Faulting & Folding (Foam Faults Demo)

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