Subduction Zone: Simplified model of elastic rebound

25s Novice

What is elastic rebound in subduction zones?

Oblique view of a highly generalized animation of a subduction zone where an oceanic plate is subducting beneath a continental plate. (See sketch below for parts.) This scenario can happen repeatedly on a 100-500 year cycle. The process which produces a mega-thrust earthquake would generate a tsunami, not depicted here.

Keypoints:

During subduction:

  • the heavier, thinner plate dives beneath the more-buoyant plate
  • Two tectonic plates are locked at the contact by immense friction.
  • The overlying plate is forced backward creating strain
  • When friction is overcome the plate rebounds along the contact to a more-relaxed position 

Related Animations

GPS can record the movement of the leading edge of the overlying continental plate in a subduction zone. The plates are locked and the overlying plate is forced back. When friction is overcome and strain is released, the GPS receiver will snap back toward its original position. 

Animation Novice

 GPS records the movement of the leading edge of the overlying continental plate in a subduction zone. The plates are locked and the overlying plate is forced back. When friction is overcome and strain is released, the GPS receiver will snap back toward its original position. 

Animation Novice

The subduction zone iswhere two tectonic (lithospheric) plates come together, one subducting (diving) beneath the other. The plates are locked together and periodically overcome the friction causing the leading edge of the overlying plate to surge back, lifting a wall of water producting a tsunami.

Animation Novice

Subduction zones show that there are 3 distinct areas of movement in the overlying plate:

  1. constant movement above the locked leading edge,
  2. see-saw pattern of back-&-forth movement above a zone that alternately locks then slips, and
  3. no movement far inland above the deeper part of the diving oceanic plate.
Animation Novice

In a reverse fault, the block above the fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening. A reverse fault is called a thrust fault if the dip of the fault plane is small. Other names: thrust fault, reverse-slip fault or compressional fault]. Examples: Rocky Mountains, Himalayas.

Animation Novice

Related Videos

Video lecture about elastic rebound and brittle material in the crust using a yardstick as a mechanical analog. This demonstrates elasticity, brittle fracture, and why it is difficult to predict earthquakes.

Video Novice

Related Lessons

Using a block-and-sandpaper model, students collaborate in small groups to investigate how energy is stored elastically in rocks and released suddenly as an earthquake (the earthquake cycle). This activity emphasizes the role of mechanical models in understanding and testing ideas in science.

Lesson Novice

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