Where does an earthquake start?
Objectives:
After performing this activity, you should be able to:
1. differentiate between focus and epicenter; and
2. demonstrate how movement along faults affect the surroundings.
Materials Needed:
fault model
scissors
paste
Procedure:
1. Photocopy the Fault Model (Figure 12; you can also trace it on paper). Then cut along the outlines of the two drawings.
2. Fold along the lines and paste where indicated. In the end, you should have a model consisting of two parts that fit together (Figure 13).
3. The upper surface of the model represents the surface of the Earth. The trace of the fault on the surface of the Earth is called the fault line. Be ready to point out the fault line when your teacher calls on you.
4. Pull the two pieces apart (Figure 14). The flat surface between the two pieces is called the fault plane. This is where fault slip or fault movement happens. Point out the fault plane when your teacher asks you.
5. The place where the fault begins to slip is called the focus. It is where the first movement occurs. Thus, the focus is the origin of the earthquake. Be ready to explain it to your teacher.
6. Put the two pieces of the model together. The focus is now hidden “underground.” Now, imagine a vertical line from the focus to the upper surface of the model. Mark the place where you expect the line to come out.
The spot directly above the focus on the surface of the Earth is called the epicenter. Show the “epicenter” of your model to your teacher.
Q9. Use your model to show different types of movement along a fault. How would the surroundings be affected?
