Earthquake Machine: Elastic Rebound & the Rock Demonstration

Can rock bend? Does rock have elastic rebound?

Demonstration shows that rocks are elastic by squeezing a slit core of solid rock. Energy is stored as potential energy while the rock is squeezed. Energy is released as kinetic energy, and the tongs return to their original position when pressure is released. This is called "elastic rebound" and is what happens along faults in the lithosphere. (John Lahr; USGS seismologist emeritus)


  • Mechanical model shows how rock behaves when pressure is applied
  • Rock is elastic, therefore the lithosphere is elastic
  • Lithospheric plates behave elastically, like huge springs
  • When elastic energy is released it produces an earthquake releasing heat and kinetic energy

Level: Novice

Share it

Related Lessons

Through a demonstration lead by the teacher, the discrepant concept of rocks exhibiting elastic behavior is physically illustrated with an easily obtained, inexpensive model.

Lesson Novice

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

Related Animations

Animation of the single-block "Earthquake Machine", a mechanical model of the earthquake process using a wood block, sandpaper, and rubber bands. This model shows how "Forces, Faults, and Friction" interact as elastic energy is slowly stored when the rubber back stretches and then is rapidly released as the block jerks during an "earthquake".

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

THE two-block "Earthquake Machine" uses two blocks with different grit sandpaper to model interactions between adjacent patches along a fault.

Video Intermediate