By | May 24, 2015

Objective: To demonstrate the forces that cause earthquakes, the tension that can build up at earthquake faults, and the ensuing debris produced at a fault.

Standards: Structure of the Earth System (plate tectonics and its relation to earthquakes) and Transfer of Energy (energy types, characteristics, and transfer properties).

Materials: One half of a graham cracker (one cracker with a perforated line down the middle).

Procedure:

(1) Break the graham cracker along the perforation.

(2) Place the two pieces back together so they are touching where they broke.

(3) Move one piece towards you and one piece away from you as you keep the pieces touching.

(4) Observe the small crumbs that form as they move against each other.

(5) Break one of the halves into two pieces. The resultant edges should not be smooth.

(6) Put the pieces back together so they are touching, just as before.

(7) Repeat step three.

(8) Note that the pieces do not move as easily as they did before.

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(9) Keep moving the pieces until they do move and observe the larger crumbs.

Science Behind It: Pushing the graham crackers past each other represents a transform fault where earthquakes occur. As the tectonic plates (or crackers) move, tension builds up causing vibrations and therefore earthquakes. The more uneven or rough the fault is, the more pressure that builds up because it is harder for the plates to move past each other. This therefore results in a much larger earthquake when the plates get past each other, resulting in the larger debris, as seen in step nine from above.