FAULTS

1. FAULT AND ITS CLASSIFICATION
GUIDED BY-
Dr. POONAM
BHATNAGAR
PRESENTED BY-
SHIVANI
THAKUR
CLASS- M.Sc.I-SEM
GOVT. HOLKAR SCIENCE
COLLEGE, INDORE (M.P.)

2. CONTENT-
❖INTRODUCTION
❖ ELEMENTS OF
FAULTS/GEOMETRY OF
FAULTS
❖CLASSIFICATION OF FAULTS
❖GEOMETRIC
CLASSIFICATION
❖GENETIC CLASSIFICATION
❖DISTRIBUTION OF FAULTS
❖MAJOR FAULTS IN INDIA
❖CONCLUSION
❖REFERENCES
San Andreas Fault in the Carrizo
Plane, western California.

3. INTRODUCTION
❖ Fault is a rupture, fracture or crack in a rock along which a
significant differential displacement of rock body has taken place
due to some compressional and tensional stresses within the rock.
❖ When the rock on one side has moved along the fracture relative to
the other side, the fracture is termed a 'fault'.
It is a planar structure always develops along a particular
plane.
Figure showing a faulted rock in
which displacement of rock blocks
along a fracture surface is seen.

4. GEOMETRY OF FAULTS
1. Fault plane:
A plane along which the rupture has actually taken place or
where one block is moved with respect to other is known as
‘Fault Plane’.
A fault plane can be classified in 3 types:
⦿ Vertical fault plane- Forming vertical fault .
⦿ Inclined fault plane- forming normal and reverse fault.
⦿ Horizontal fault plane- Horzontal fault .
For faults having inclined fault plane (not for vertical) the
following terminology is used:-
1.Dip and Strike: The inclination of a fault plane may be given
as a dip (angle between horizontal surface and fault plane)
and the strike is the trend of a horizontal line in the fault
plane .
2. Hanging wall and Footwall:
The block above the fault plane is called ‘Hanging wall’. And
The block below the fault plane is called the Footwall.
3. Hade: It is the inclination of the fault plane that is vertical.

5. 4. Throw: It is the vertical
displacement between the
Hanging wall and Footwall.
5. Heave : It is the horizontal
displacement between the
Hanging wall and footwall
6. Rake: the angle between a
line (or a feature) and the
strike line of the fault plane.
A planar fault is defined by
the strike and dip of the fault
surface and the direction of
the slip vector. {λ-Rake, φ-
plunge}

6. CLASSIFICATION OF FAULTS-
FAULTS CAN BE CLASSIFIED IN TWO TYPES-
1. GEOMETRIC CLASSIFICATION
2. GENETIC CASSIFICATION
GEOMETRIC CLASSIFICATION-
Faults can be classified on the basis of their geometry or their
genesis. Geologists consider geometric classification at first as
they are less hazardous than genetic because no interpretation
is involved in them.
The basis of 5 different geometric classification are-
⦿ The rake of the net slip
⦿ The attitude of the fault relative to the attitude of relative rock
⦿ The pattern of the faults
⦿ The angle at which the fault dip
⦿ The apparent movement on the fault

7. On the basis of rake of net slip-
Strike-slip fault-
Fault in which the net slip is parallel to the strike and dip slip
component is absent , That is the rake of net slip is zero is
known as strike-slip fault.
Dip-slip fault-
Fault in which dip slip is equal to the net slip and there is no
strike slip component ,That is the rake of net slip is 90 degree
is known as dip-slip fault.
Diagonal-slip fault-
fault in which both strike-slip and dip-slip components are
present and rake of the net slip is <0 and >90 are termed as
Diagonal-slip fault.

9. Classification of faults based on the dip of the fault plane and the pitch,
the strike. Based on Angelier (1994).

10. ON THE BASIS OF ATTITUDE OF FAULT-
Strike fault- Fault that strikes essentially parallel to the strike
of adjacent rock is termed as strike fault.
Bedding fault- it is a strike fault that is parallel to the bedding.
Dip fault- it strikes essentially parallel to the dip of the
adjacent beds.
Oblique or Diagonal fault- it strikes obliquely of diagonally to
the strike of the adjacent rocks.
Longitudinal fault-it strikes parallel to the strike of the
regional structure like fold etc.
Transverse fault –it strikes perpendicularly or diagonally to
the strike of the regional structure.

11. Fig. Showing Longitudinal And
Transverse Faults
FIg Showing Bedding and Dip Faults

12. ON THE BASIS OF FAULT PATTERN-
Parallel faults- The faults have essentially same dip and strike ,
there fault planes are parallel to each other are termed as parallel
fault.
En echelon faults- these are closely spaced, parallel or sub
parallel, step like short faults that overlap each other.
Peripheral faults- these are circular or arcuate faults that bound
a circular area or a part of it.
Radial faults- these faults belong to a system of fault that radiate
out of a point.

13. A) Parallel Fault B) En-Echelon Fault C) Concentric Fault D) Radial Fault

14. On The Basis Of Amount Of Dip Of Fault-
Low angle faults- faults that dip less than 45 degree are termed
as low angle faults.
High angle fault- are those that dip more than 45 degee.

15. ON THE BASIS OF APPARENT MOVEMENT-
Three fundamental types of faults are commonly distinguished on the
basis of apparent Movement:
1. Apparent Normal fault- Such a fault in which hanging wall has
apparently moved down with respect to foot wall is classified as a
apparent Normal Fault.
2. Apparent Reverse Faults: fault in which the hanging wall appears to
have relatively moved up with respect to the foot wall is termed as
apparent reverse fault and some times termed as apparent thrust fault.
3. Strike-slip fault- in which the movement along the fault is parallel to
the strike of the fault.

16. Piqiang Fault, Northwest trending left lateral strike-slip fault,
in Taklamakan Desert, China.

17. GENETIC CLASSIFICATION-
The most satisfactory genetic classification is based on the
relative movement along the fault.
❖ Normal fault/gravity fault- Such a fault in which hanging wall
has a moved relatively down with respect to foot wall is known
as Normal Fault and also as gravity fault.
❖ Detachment fault-it is a special category of low –angle normal
faults formed due to gravitational instability of uplifted region.
❖ Graben- A graben is an elongated wedge shaped central block,
which has moved downward with respect to the side blocks
along two downward converging normal faults. The bordering
faults are almost parallel in strike and high angled in character.
Major graben which extend for long distance are termed as
RIFTS.
❖ Horst- When two normal faults appear on either side of a
central wedge shaped elongated block, which appears raised
high up with respect to the sides, the outstanding structure is
called a Horst.

18. Showing a Normal fault
or a Gravity Fault or
Detachment Fault.
Normal Fault in LA
Herradura Formation,
Morro Solar, Peru.

19. Normal Fault In
Spain, Forming
Graben structure.
Both Emages Showing Horst and Graben Near Zarjan, Iran.

20. ❖Strike-slip fault/ wrench fault- are those along which
displacement has been essentially parallel to the strike of the fault
,that is dip-slip component is very small or absent. Strike-slip faults
also known as lateral faults, transverse faults, wrench faults,
transcurrent fault, tear fault and transform faults.
❖Left lateral fault/Sinistral fault/Left slip fault-
when in strike-slip or lateral fault displacement of block is in left
side to the observer then it is termed as left lateral fault or Sinistral
fault or left-slip fault.
❖Right lateral fault/Dextral fault/Right slip fault-
when in strike-slip or lateral fault displacement of block is in right
side to the observer then it is termed as right lateral fault or Dextral
fault or right-slip fault
❖Dip slip fault- faults in which displacement has been essentially
parallel to the dip of the fault plane.

22. ❖Reverse fault- faults in which the hanging wall appears to have
moved up with respect to the foot wall is termed as reverse faults,
in which the fault plane dips more than 45 degrees.
❖Thrust fault- It is a low angle reverse fault in which fault plane
dips less than 45 degree.
❖Under thrust fault- it is a thrust fault in which the foot wall
moved and the hanging wall did not.
❖Over thrust fault- it is a thrust fault that dips less than 10
degree and has a large net slip. In such faults the hanging wall has
been the active element not the foot wall.
❖Up thrust fault- it is a high angle thrust fault in which hanging
wall is an active element.

23. Reverse Fault
Over Thrust Fault

24. Reverse Fault Zone, Ketobe Knob, Utah (Jurassic Stratigraphy of
Colarado Plateau US.)

25. ❖Nappe- A nappe or thrust-sheet is a large sheet like body of rock
that has been moved more than 2 km or 5 km often ranging to
several hundred kilometers, along a thrust plane from its original
position.
❖Listric fault- A listric fault is a curved normal fault which
achieves a rotation in the hanging wall as a geometric consequence
of the displacement, (the fault plane is concave upward its dip
decreases with depth) .
❖Hinge fault- These are also called pivotal faults or rotational
faults. A hinge fault is characterised by a movement of the disrupted
blocks along a medial point called the hinge point. The movement is,
therefore, rotational rather than translational . In such faults, the
amount of displacement increases away from the hinge point.

27. ❖ Ring fault -
Ring faults, also known as caldera
faults, are faults that occur within
collapsed volcanic calderas and the
sites of bolide strikes, such as the
Chesapeake Bay impact crater. Ring
faults are result of a series of
overlapping normal faults, forming a
circular outline.
❖ Synthetic and Antithetic Fault-
Synthetic and antithetic faults are
terms used to describe minor faults
associated with a major fault.
Synthetic faults dip in the same
direction as the major fault while the
antithetic faults dip in the opposite
direction.

28. DISTRIBUTION OF FAULTS-
❖ A map of global tectonic and volcanic activity over the last
one million years, showing: active ridges, continental
extensions, transform faults, ridge spreading rates and
directions, continental rifts, subduction and overthrust zones,
and generalized volcanic activity. Illustration prepared by
Paul D. Lowman Jr., NASA Goddard Space Flight Center.

30. MAJOR FAULTS IN INDIA-
❖ Integration of geological/geomorphic and seismological data has
led to the identification of 67 active faults of regional scale, 15 in
the Himalaya, 17 in the adjoining foredeep with as many as 30
neotectonic faults in the stable Peninsular India.
❖ Major faults of India are Main Central Thrust, Main Boundary
Thrust and Himalayan Frontal Thrust in the Himalayan collision
zone; Mishmi thrust, Lohit thrust, Kopili fault in the North-East
(NE) Indian region; Narmada-Son-Tapti and Godavari rift zones in
the peninsular India; Allah Bund fault, Kuchch Mainland fault,
Katrol Hill fault and Bhuj fault in the western Indian region; and N–
S trending faults in the Andaman Sumatra subduction zone.
❖ Map of Peninsular India displaying the eleven seismic source zones.
The background illustrates the faults digitized from the
seismotectonic atlas (GSI 2000).

31. ❖ Illustration of Faults in Great Himalaya And Tibetan Zone:

32. ❖ Illustration of Major faults of Peninsular India:

33. CONCLUSION-
❖ Faulting is a major tectonic process of great geological importance.
The geological history of the Earth bears innumerable events
recorded major faulting processes.
❖ The mechanism of faulting is based on the plate tectonic theory as all
plate boundaries are the zone of faulting such like transform plate
boundaries.
❖ Study of faults is also useful Economic geology as hydrothermal ore
deposits originate associated with regional fault places
❖ The study of faults is essentially important for civil engineering
works.
❖ The study of faults and their accurate recognition is of great
importance for the disaster Management. Many destructions can be
precured and mitigated by preducting them.

34. REFERENCES-
❖ Billings ,M.P. Structural Geology Published in NY: By Prentice-
Hall (1946). Page no.(175 to 190)
❖ Haakon Fossen, Structural Geology, NY:Published by Cambridge
University Press (2010). Page No. (151-181)
❖ Park, R.G. Foundation Of Structural Geology, 3rd edition
published by Chapman Hall. Page No.(9 to10)
❖ Twiss, R.J. & Moores, E.M. Structural Geology, 2nd ed.
Published by Susan Finnemore Brennan. Page No. (61-149)
❖ https://en.m.wikipedia.org (Accesed on 3 October 2019)
❖ http://www.geographynotes.com (Accesed on 3 October 2019)

35. THANK YOU