This document summarizes a seminar on faults presented by Aditi Jena to her professor. It defines a fault as a fracture in rock across which there is significant displacement. Faults are classified based on their dip, pattern of movement, and stress conditions. The main types are normal faults which form during tension, reverse/thrust faults during compression, and strike-slip faults when the intermediate stress axis is vertical. Fault planes develop at 30 degrees to the maximum stress and slip occurs perpendicular to the intermediate stress. Examples like the San Andreas fault and Main Central Thrust are given to illustrate different fault types.

1. DR HARSINGH GOUR
UNIVERSITY
SAGAR , (M.P)
A SEMINAR ON FAULT, CLASSIFICATION OF
FAULT AND MECHANISM OF FAULTING
2018-19
UNDER THE SUPERVISION SUBMITED BY:
OF: Prof. A.K.SHANDILYA ‘sir’ ADITI JENA
M.TECH 1ST SEM
Y18251002
1ST SEM

2. CONTENTS
1. INTRODUCTION
2. ELEMENTS OF FAULT
3. CLASSIFICATION OF FAULT
4. MECHANISM OF FAULT
5. REFERENCE

3. FAULT
 In geology, a fault is a planar fracture
or discontinuity in a volume of rock,
across which there is significant
displacement as a result of rock mass
movement.
 Large faults within the earth’s crust
result from action of plate tectonic
forces, with the largest forming the
boundaries between the plates, such
as subduction zones or transform
fault.

5. ELEMENTS OF FAULT

6. FAULT PLANE: It is a planar surface along which
there is relative displacement of blocks taking
place during faulting.
FAULT LINE: Line of intersection of fault plane
with the ground surface.
HANGING WALL AND FOOT WALL : The block
lying above the fault plane or the block which is
free to move is called hanging wall and the block
which lying below the fault plane or which
remain stationary is called foot wall block.
DIP OF THE FAULT : The inclination of the fault
plane with its horizontal projection is the dip of
the fault.

7. STRIKE OF THE FAULT : The trace of the
fault plane on the horizontal surface is
called the strike.
SLIP OF THE FAULT: Describes the
movement parallel to the fault plane.
NET SLIP: Total amount of displacement
measured parallel to direction of motion.
RAKE OF NET-SLIP: The angle between
horizontal(strike) and the net slip vector
measured on vertical plane.

9. Based on rake of net slip:
STRIKE SLIP FAULT : Where the net slip is
parallel to the strike of fault and rake of the net slip
is equal to zero.

10. DIP SLIP FAULT:
Where the net slip is
equal to dip of fault.
Rake of net slip is
therefore 90º
DIAGONAL SLIP
FAULT: Where
there is both strike
slip and dip slip
component. Rake of
net slip is more than
0ºbut less than 90º.

11. Based on attitude of fault

12. Pattern Of Fault

13. DIP OF FAULT

14. APPARENT MOVEMENT OF FAULT

15. Genetic classification
1. Normal Fault: Hanging
wall has moved relatively
downward. It is further
divided in to two
subclasses on the basis of
amount of dip.
I. High angle Normal fault:
those that dip greater
than 450.
II. Low Angle Normal
Fault: Those that dip less
450.

16. 2. Reverse Fault
I. High Angle
Reverse
Fault:
Amount of Dip
more than
450.
II. Low Angle
Reverse
Fault:
Amount of Dip
less than 450.
Hanging wall has moved upward relative to the
footwall

17. 3. Thrust Fault:
Hanging wall has moved upward relative to footwall.
I. Over Thrust : Here the
initial dip is less than
100.
II. Under Thrust Fault: the
footwall side actually
moved and pushed it
self under neath the
Hanging wall side.

18. Nappe:
Word was coined by Prof. W.D.West
In geology, a nappe or thrust sheet
is a large sheet like body of rock
that has been moved more than
2km or 5km above a thrust fault
from its original position.
Example: Deolapar nappe
Nappe
Prof. W.D.West

20. STRESS AND STRAIN
 Force acting per unit
area is called STRESS
 Amount of deformation
an object experiences
after stress applied is
called STRAIN which
also depend upon
temperature , pressure
and mineral composition
of rock

21. STRESS ELLIPSOID

22. STRAIN ELLIPSOID
 Strain ellipsoid
is the
geometric
representation
of three
dimensional
strain that
develops
during
deformation.

23. MECHANISM OF FAULTING IN RELATION
TO STRESS AND STRAIN AXES

24. SOME RULES
 Fault plane must pass through the
principal axis of intermediate stress.
 Fault plane must exhibit angle of 30º
with respect to principal axis of
maximum stress.
 Displacement should be perpendicular
to principal axis of intermediate stress.

25. In case of normal fault
Normal faults occur due to
tensional stress.
In case of normal fault the
greatest principal
axis is vertical while intermediate
and least principal axes are
horizontal.
So normal fault is characteristic
of divergent plate boundaries.

26. Normal fault near entrance of
Arche National Park, Utah

27. In case of thrust fault
 Here greatest principal stress axis
and intermediate principal stress
axis are horizontal while least
principal stress axis is vertical.
 Formed due to compression stress.
 Example: Main Central Thrust is a
major geological fault where the
Indian plate pushed under the
Eurasia plate along Himalaya.

28. MAIN CENTRAL THRUST

29. In case of strike slip fault
Here the IPSA is vertical, and
greatest and least principal
stress axes are horizontal.
This condition lead to
movement of block parallel to
the strike.

30. San Andreas Fault
Tectonic boundary between
North America and Pacific plate

31. REFERENCE
 Billings P.M, Structural Geology 3rd
edition.
 Jain .K.A, Introduction to Structural
Geology
 Google
 Class notes