GRADE VI
WHY EARTHQUAKES OCCUR
At the end of this module, you should able to:


Demonstrate how blocks of rock/plates move along faults of the earth’s crust
Illustrate the three types of plate movement
Explain how earthquakes occur
Try to Recall
1. Have you experienced an earthquake? How did you feel?
2. What can you observe after an earthquake?
3. Study the pictures. Take note of the changes which take place in each set of pictures.
A
B
C
D
1. Describe the change which takes place in each set of picture.
A. ___________
B. ___________
C. ___________
D. ___________
2. What caused these changes to happen?
1
Explore
Activity 1
1. Secure the following.
8 books
sheet of paper
any small objects
2. Make a pile of books on the table as shown. The books represent layers of bedrocks
in the earth’s crust.
3. Place a sheet of paper on top of the pile. Then put the small objects on the sheet of
paper.
4. Pull one book at the bottom of a pile.
5. Observe what happen.
6. Answer these questions in your notebook.
a. What happens to the pile?
b. When this pile moves down, what happens to the objects above the pile?
Activity 2
1. Have the following materials.
bar soap, knife
2. Cut the soap diagonally into three parts.
3. Push the soap towards each other. Observe.
4. Pull the soap away from each other. Observe the pieces of soap horizontally against
each other.
5. Observe.
2
Answer these question in your notebook.
1.
2.
3.
4.
What happened when you push the soap toward each other?
How about when you pull the soap away from each other?
When the soap slides past one another, what is the result?
Suppose the soap represents the rocks/plates beneath the crust, what do you
think will be the result of these movements?
5. What are the three types of plate movements?
6. Why do you think cause the plates to move?
7. How do you think does an earthquake occur?
Read and learn more.
Earthquakes are ground vibrations caused by the release of
energy that accompany fault movement, asteroid impact, volcano
eruptions, movement of magma, or explosions. These vibrations or
shaking are waves travelling through the earth away from the location
where they originated. The point of origin of the earthquake is called
focus (plural-foci) and the point about the earth’s surface the point
above the focus is called the epicenter.
These are two general earthquake waves: body wave which
travel through the interior of the mass in which they are generated and
the surface wave which travel only along the surface.
Earthquakes are classified as tectonic, or volcanic. The
earthquake that is caused by the movement of the earth’s crust it is
called tectonic earthquakes; when it is caused by volcanic eruption it is
known as volcanic earthquake.
I LEARNED THAT:


Earthquake is the shaking or ground vibration caused by large release of energy.
Earthquakes occur along faultline.
3
Apply It
A. Complete the table below. Copy the table in your notebook.
Earthquake
What I Know
What I Want to Know
What I Learned
B. You are on the 10th floor of a 15-storey building. An earthquake occurred. What
would you do? Why?
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
4
Test Yourself
*
A. Draw the three types of plate movement. Use an arrow.
Push each other
(Move toward each other)
Pull each other
(Move away from each other)
B. Describe how an earthquake happens.
5
Slide past one
another