Graham Cracker Earthquake

Area of Science: Earth Sciences
Meant for at least Grade K-3 (age 5-7).
This experiment is edible.
An adult need not be present.

Overview:
The experiment demonstrates the forces that create earthquakes. It also shows the tension that can build up before a quake and the resultant debris created along a fault.

Equipment:
You will need one half of a graham cracker (one cracker with a perforated line down the middle)

Safety:
None

How to do the experiment:

  1. Break the graham cracker along the perforation.
  2. Place the two pieces back together so they touch.
  3. Move one piece away from you and one piece toward you keeping the edges touching.
  4. Observe the tiny crumbs that form as they move side by side. These represent rocks breaking off the edges of two plates along a fault.
  5. Now break one of the halves into two pieces. Notice that the edge is not smooth like the first two pieces you made.
  6. Put the broken edges back together like you did with the first break.
  7. Move one piece away from you and one toward you with the broken edges touching.
  8. Notice that the two do not move as easily this time. This is the tension that builds up along a fault before an earthquake.
  9. Keep moving the halves until they move. Notice the large pieces that break off. This represents a very much larger earthquake than the first time. It is much more destructive.
  10. Put some peanut butter on the pieces and eat the evidence.
Explanation:
Earthquakes occur where there are breaks in the crust of the earth. Usually there are large plates of crust that move against each other. When the plates move side by side the rubbing together makes vibrations and these are earthquakes. The sliding plates grind off pieces of rock as they move. If the fault (break) is very uneven there can be a build up of extreme pressure. This will cause a much larger earthquake (vibration) when the rocks break or slip past each other.

Useful References:

  • Earth Science Geology, the Environment, and the Universe; Hess, et al.; McGraw-Hill Glencoe, 2005 ISBN0078664233
  • Try the MadSci Search engine with queries such as earthquakes plates and earthquakes plate tectonics

    Further comments:
    I made this lab up while I was a teacher of 7th grade Earth Science. I use a variation of this to show mid ocean ridge formation. Just add a blob of peanut butter, place the edges together on top of the peanut butter, and while applying a downward pressure, slide the pieces apart.

    Experiment submitted on Wed Jun 1 14:08:17 2005 by:
    Name: Charles Wolf
    Institution: McGraw-Hill Glencoe
    Position: editor
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