Faults are fractures with movement parallel to their plane, usually caused by seismic activity. Understanding faults is important for engineering structures. There are three main types of faults - normal, thrust, and strike-slip. Normal faults involve the hanging wall moving down relative to the footwall. Thrust faults involve the hanging wall moving up. Strike-slip faults involve lateral movement along the fault plane. Faults can be identified by features like slickensides, mineral growth, and offset stratigraphy. Fault classification helps understand mountain building and plate tectonics. Careful analysis of faults is necessary for safe construction near fault lines.

1. University of Azad Jammu
and Kashmir
Raja Saad Qamar
TOPIC FAULTS

3. FAULT CLASSIFICATION ANDFAULT CLASSIFICATION AND
TERMINALOGYTERMINALOGY
Faults:Faults:
Are fractures that have appreciableAre fractures that have appreciable
movement parallel to their plane.movement parallel to their plane.
They produced usually by seismicThey produced usually by seismic
activity.activity.
Understanding faults is useful inUnderstanding faults is useful in
design for long-term stability ofdesign for long-term stability of
dams, bridges, buildings and powerdams, bridges, buildings and power
plants. The study of fault helpsplants. The study of fault helps
understand mountain building.understand mountain building.

4. Parts of the FaultParts of the Fault Fault planeFault plane: Surface that the movement hasSurface that the movement has
taken place within the fault.On this surfacetaken place within the fault.On this surface
the dip and strike of the fault is measured.the dip and strike of the fault is measured.
 Hanging wall:Hanging wall: The rock mass resting on theThe rock mass resting on the
fault plane.fault plane.
 Footwall:Footwall: The rock mass beneath the faultThe rock mass beneath the fault
plane.plane.
 Slip:Slip: Describes the movement parallel to theDescribes the movement parallel to the
fault plane.fault plane.
 Dip slip: Describes the up and downDip slip: Describes the up and down
movement parallel to the dip direction of themovement parallel to the dip direction of the
fault.fault.
 Strike slip:Strike slip: Applies where movement isApplies where movement is
parallel to strike of the fault plane.parallel to strike of the fault plane.
 Oblique slip:Oblique slip: Is a combination of strike slipIs a combination of strike slip
and dip slip.and dip slip.
 Net slip (true displacement): Is the totalNet slip (true displacement): Is the total
amount of motion measured parallel to theamount of motion measured parallel to the
direction of motiondirection of motion

5.  Separation:Separation: The amount ofThe amount of
apparent offset of a faultedapparent offset of a faulted
surface, measured in specifiedsurface, measured in specified
direction. There are strikedirection. There are strike
separation, dip separation, andseparation, dip separation, and
net separation.net separation.
 Heave:Heave: The horizontalThe horizontal
component of dip separationcomponent of dip separation
measured perpendicular to strikemeasured perpendicular to strike
of the fault.of the fault.
 Throw:Throw: The vertical componentThe vertical component
measured in vertical planemeasured in vertical plane
containing the dip.containing the dip.

6. Features on the fault surfaceFeatures on the fault surface
 GroovesGrooves (parallel to the(parallel to the
movement direction)movement direction)
 Growth of fibrous mineralsGrowth of fibrous minerals
(parallel to the movement(parallel to the movement
direction)direction)
 SlickensidesSlickensides are the polishedare the polished
fault surfaces.fault surfaces.
 Small steps.Small steps.
All are considered a kind ofAll are considered a kind of
lineation. They indicate thelineation. They indicate the
movement relative trend NW,movement relative trend NW,
NE … etc.NE … etc.
Small steps may also be used toSmall steps may also be used to
determine the movementdetermine the movement
direction and direction ofdirection and direction of
movement of the opposingmovement of the opposing
wall. Slicklines usuallywall. Slicklines usually
record only the last momentrecord only the last moment
event on the fault.event on the fault.

7. ANDERSON FAULTS CLASSIFICATIONANDERSON FAULTS CLASSIFICATION
Anderson (1942) definedAnderson (1942) defined
three types of faults:three types of faults:
 Normal FaultsNormal Faults
 Thrust FaultsThrust Faults
 Wrench FaultsWrench Faults
(strike slip)(strike slip)

8. Different Type of Faults

9. Normal FaultNormal Fault
Normal Fault: The hanging wall has moved down
relative to the footwall.
Graben:Graben: consists of a block that has dropped downconsists of a block that has dropped down
between two subparllel normal faults that dip towardsbetween two subparllel normal faults that dip towards
each other.each other.
HorstHorst :: consists of two subparallel normal faults that dipconsists of two subparallel normal faults that dip
away from each other so that the block between the twoaway from each other so that the block between the two
faults remains high.faults remains high.
Listric:Listric: are normal faults that frequently exhibit (concave-are normal faults that frequently exhibit (concave-
up) geometry so that they exhibit steep dip near surfaceup) geometry so that they exhibit steep dip near surface
and flatten with depth.and flatten with depth.
Normal faults usually found in areas where extensional stress isNormal faults usually found in areas where extensional stress is
presentpresent..

10. Normal FaultsNormal Faults

11. Thrust FaultThrust Fault
Thrust Faults: In the thrust
faults the hanging wall
has moved up relative to
the footwall (dip angle
30º or less)
Reverse Faults: Are similar
to the thrust faults
regarding the sense of
motion but the dip angle
of the fault plane is 45º
or more
Thrust faults usuallyThrust faults usually
formed in areas offormed in areas of
comperssional stress.comperssional stress.
Thrust FaultThrust Fault

12. Thrust FaultsThrust Faults

13. Strike-Slip FaultStrike-Slip Fault
Strike-slip Faults: Are faults
that have movement along
strikes.
There are two types of strike
slip faults:
A] Right lateral strike-slip fault
(dextral): Where the side
opposite the observer moves
to the right.
B] Left lateral strike-slip fault
(sinistral): Where the side
opposite the observer moves
to the left.
Note that the same sense ofNote that the same sense of
movement will also bemovement will also be
observed from the other sideobserved from the other side
of the fault.of the fault.
Strike-SlipStrike-Slip
FaultsFaults

14. Transform FaultsTransform FaultsTransform Faults:Transform Faults: Are aAre a
type of strike-slip faulttype of strike-slip fault
(defined by Wilson 1965).(defined by Wilson 1965).
They form due toThey form due to thethe
differences in motiondifferences in motion
between lithosphericbetween lithospheric
plates.plates. They areThey are
basically occur wherebasically occur where
type of plate boundarytype of plate boundary
is transformed intois transformed into
anotheranother..
Main types of transformMain types of transform
faults arefaults are::
 Ridge-RidgeRidge-Ridge
 Ridge-ArcRidge-Arc
 Arc-ArcArc-Arc

15. Other types of faultOther types of fault
 en-echelon faults:en-echelon faults: Faults thatFaults that
are approximately parallel oneare approximately parallel one
another but occur in shortanother but occur in short
unconnected segments, andunconnected segments, and
sometimes overlapping.sometimes overlapping.
 Radial faults:Radial faults: faults that arefaults that are
converge toward one pointconverge toward one point
 Concentric faults:Concentric faults: faults that arefaults that are
concentric to a point.concentric to a point.
 Bedding faults (bedding planeBedding faults (bedding plane
faults):faults): follow bedding or occurfollow bedding or occur
parallel to the orientation ofparallel to the orientation of
bedding planes.bedding planes.

16. CRITERIA FOR FAULTINGCRITERIA FOR FAULTING
 Repetition or omissionRepetition or omission of stratigraphic units asymmetricalof stratigraphic units asymmetrical
repetitionrepetition
 Displacement of recognizable markerDisplacement of recognizable marker such as fossils,such as fossils,
color, composition, texture ..etc.)color, composition, texture ..etc.)..
 Truncation of structuresTruncation of structures, beds or rock units., beds or rock units.
 Occurrence of fault rocksOccurrence of fault rocks (mylonite or cataclastic or both)(mylonite or cataclastic or both)
 Presence of S or C structuresPresence of S or C structures or both, rotated porphyryor both, rotated porphyry
clasts and other evidence of shear zone.clasts and other evidence of shear zone.
 Abundant veinsAbundant veins, silicification or other mineralization along, silicification or other mineralization along
fracture may indicate faulting.fracture may indicate faulting.
 Drag UnitsDrag Units appear to be pulled into a fault duringappear to be pulled into a fault during
movement (usually within the drag fold and the result ismovement (usually within the drag fold and the result is
thrust fault)thrust fault)
 Reverse dragReverse drag occurs along listric normal faults.occurs along listric normal faults.
 SlickensidesSlickensides and slickenlines along a fault surfaceand slickenlines along a fault surface
 Topographic characteristicsTopographic characteristics such as drainges that aresuch as drainges that are
controlled by faults and fault scarps.controlled by faults and fault scarps.

17. conclusion
Faults are the geological structure which
sometimes causes serious damaging along
the fault line.
Fault may causes the earthquakes which
disturbs constructions ,dams, bridges,
buildings and even the whole communities
Government must have to stop and banned the
construction along the fault line, to save the
precious life loses.

18. References
www.eeescience.utoledo.edu
Web.njcu.edu/sites
Faculty.kfump.edu.sa