focus and epicenter

1. GOOD DAY EVERYONE!

3. THE FOCUS AND EPICENTER
OF AN EARTHQUAKE
MA’AM JEN

4. PARTS OF A FAULT
• Hanging Wall- the block above the fault.
• Foot Wall- the block below the fault.
• Fault Plane- is the plane that represents the
fracture surface of a fault.
• Fault Scarp- is a small step or offset on the
ground surface where one side of a fault has
moved vertically with respect to the other.
• Fault Line- is a place where the fault can be
seen or mapped on the surface.

5. THE FOCUS AND EPICENTER
FOCUS (HYPOCENTER)-
(hypo means under or
beneath). The focus is the
origin or the center of the
earthquake. It is located
underground. The point within
earth where rock under stress
breaks is called focus.

6. THE FOCUS AND EPICENTER
EPICENTER- (epi means
surface) A point on the
surface of an earthquake
which is directly above the
focus of an earthquake and
where the earthquake
vibrations reach first. Usually
what is used to locate the
position of an earthquake.

7. WHAT’S MORE?
Using your fault model, trace the
epicenter of an earthquake.

8. ACTIVITY 1.3
In a ¼ sheet of paper, differentiate
the epicenter of an earthquake
from its focus.

9. ASSESSMENT
Directions: Write your answer at the back of your ¼ sheet of paper.
1. Is the origin or the center of the earthquake.
a. Fault Line
b. Fault Plane
c. Epicenter
d. Focus

10. 2. A point on the surface of an earthquake which is directly above
the focus of an earthquake and where the earthquake vibrations
reach first.
a. Fault Line
b. Fault Plane
c. Epicenter
d. Focus

11. 3. Is the plane that represents the fracture surface of a fault.
a. Fault Line
b. Fault Plane
c. Foot Wall
d. Hanging Wall

12. 4. Is the block above the fault.
a. Fault Line
b. Fault Plane
c. Foot Wall
d. Hanging Wall

13. 5. Is the block below the fault.
a. Fault Line
b. Fault Plane
c. Foot Wall
d. Hanging Wall

14. ANSWER:
1.D
2.C
3.B
4.D
5.C