Home | Session 2 | Faults 1, 2, 3, 4, 5

Faults: A USGS Teacher's Lesson

Exploration Phase - Part 3
Have students develop a model of a strike-slip fault. Instructions to students:

a. Locate points F and G on your model. Move the pieces so that point F is next to point G.

b. Draw an overhead view of the surface as it looks after movement along the fault.

Concept Development - Part 3

1. Ask the following questions:

   a. If you were standing at point F and looking across the fault, which way did the block on the opposite side move?

   b. What happened to rock layers X, Y, and Z?

   c. Are the rock layers still continuous?

   d. What probably happened to the river? the road? the railroad tracks?

   e. If the scale used in this model is 1 mm = 2 m, how many meters did the earth move when the strike-slip fault caused point F to move alongside point G? (At this scale, the railroad track would be unreasonably large!) An offset of this size would be about five times that of the 1906 San Andreas earthquake.

   f. Is this type of fault caused by tension, compression, or shearing?

2. Explain that this type of fault is known as a strike-slip fault.
3. Have students label their drawing "strike-slip fault."
4. Explain that a strike-slip fault has right-lateral or left-lateral movement. As you look across the fault, the direction that the opposite side moved defines whether the movement is left-lateral or right-lateral. California's San Andreas and Hayward faults are right-lateral.

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updated January 28, 2002

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