A fault is a break or fracture between two blocks of rocks in response to stress. One block has moved relative to the other block. The surface along which the blocks move is called a fault plane. Faulting produced the earthquakes. Thus earthquakes may occur because: a) Rocks are initially broken to produce a fault. b) Movement or re-activation of an already existing fault.

2. DEFINITION OF FAULT
A fault is a break or fracture between two
blocks of rocks in response to stress.
One block has moved relative to the other
block.
The surface along which the blocks move is
called a fault plane.

3. RELATIONSHIP OF FAULT AND EARTHQUAKE
Faulting produced the earthquakes.
Thus earthquakes may occur because:
a) Rocks are initially broken to produce a fault.
b) Movement or re-activation of an already
existing fault.

4. Fault Movement = Earthquakes
An earthquake is caused by a sudden slip on a fault.
The tectonic plates are always slowly moving, but
they get stuck at their edges due to friction. When
the stress on the edge overcomes the friction, there
is an earthquake that releases energy in waves that
travel through the earth's crust and cause the shaking
that we feel.

5. Focus- where the slip happens below ground
Epicenter-where the shaking is first felt above
ground directly above the focus.

6. Three types of stresses produce faults:
1) Tension- causes rocks to stretch and also
break to produce a fault.
2) Compression- causes rocks to fold and
ultimately break to produce a fault.
3) Shear- forces producing shear strain

7. TERMINOLOGY
STRIKE – a horizontal line along the direction of a
fault plane.
DIP – the angle between the fault plane and the
horizontal.
Hanging wall – is the block above the fault plane.
Foot wall - is the block below the fault plane.

8. Three major Faults
Strike-slip
Reverse
Normal

9. Normal Fault
The hanging wall moves down relative to the foot wall.
This fault type is caused by tensional stress.

10. Normal Fault

11. Normal Fault

12. Normal Fault

13. Reverse Fault
The hanging wall
moves up relative to
the foot wall.
This fault is caused by
Compressional stress.

14. Reverse Fault

15. Reverse Fault

16. Reverse Fault

17. Strike-Slip Fault
The fault exists
between two pieces
of crust and the
Movement occurs
horizontally where
the sides slide past
each other.
This fault type is caused by shear stress.

18. Strike-Slip Fault

19. Strike Slip Fault

20. Strike-Slip Fault