Transcript Presentation on Terminology and different types of Faults

Presentation on
Terminology and different types of
Faults
Prepaid by :-
Sr no.
1.
Name
Kharadi chetan R.
Submit to :- Prof. Darshika Shah
Branch :- Civil eng.
Enrollment number
140813106002
Terminology
1) Fault plane
 Faults may be vertical, horizontal, or inclined at any angle.
 Although the angle of inclination of a specific fault plane tends to
be relatively uniform, it may differ considerably along its length from
place to place.
 When rocks slip past each other in faulting, the upper or overlying
block along the fault plane is called the hanging wall, or headwall.
2) Fault trace
 A fault trace is the intersection of a geological fault with the ground
surface, leaving a visible mark.
 The term also applies to a line plotted on a geological map to represent a
fault.
3) Fault zone
 In many cases, faulting takes place along a number of
parallel fractures.
 That is, total displacement is contributed over this zone.
 Such a zone with contains a number of closely spaced
sub-parallel fractures along which the relative
displacement has taken place is called fault zone.
4) Dip
 The dip gives the steepest angle of descent of a
tilted bed or feature relative to a horizontal
plane, and is given by the number (0°-90°) as
well as a letter (N,S,E,W) with rough direction
in which the bed is dipping.
 One technique is to always take the strike so the
dip is 90° to the right of the strike, in which case
the redundant letter following the dip angle is
omitted.
 The map symbol is a short line attached and at
right angles to the strike symbol pointing in the
direction which the planar surface is dipping
down.
 The angle of dip is generally included on a
geologic map without the degree sign. Beds that
are dipping vertically are shown with the dip
symbol on both sides of the strike, and beds that
are flat are shown like the vertical beds, but with
a circle around them.
5) Strike
 The strike line of a bed, fault, or other planar feature, is a line
representing the intersection of that feature with a horizontal
plane.
 On a geologic map, this is represented with a short straight line
segment oriented parallel to the strike line.
 Strike can be given as either a quadrant compass bearing of the
strike line or in terms of east or west of true north or south, a
single three digit number representing the azimuth, where the
lower number is usually given, or the azimuth number followed
by the degree sign.
6) Hade
 Hade is the angle which the fault plane make with
the vertical.
 Hade = 90’ – dip of the fault.
7) Throw
 The vertical component of the displacement of fractured
rock blocks, is called the throw of fault.
 The side on which the strata appear to have thrown is
called the ‘down throw side’.
 The side on which the strata appear to have gone up is
called the ‘up throw side’.
8) Heave
 The horizontal component of displacement of a
fault is called the heave.
9) Net slip
 The total displacement measured along the fault
plane is called the net slip
10) Hanging wall & Foot wall
• If the fault plane is inclined, the block lying over the fault is called
the Hanging wall.
• Whereas the block lying beneath the fault plane is called footwall.
C l a ssif ication of
Fa u l ts
[A] On the basis of the apparent
movement of the fault blocks
1) Normal Fault
 Normal fault is one in which
the hanging wall falls
down relative to the foot wall
due to tensional stress it is
also called gravity
fault/apparent normal fault.
 Normal faults with very
shallow dipping fault planes
(<10 degrees) are called
"detachment" faults or
"decollemonts".
2) Thrust Fault
 A thrust fault is a type of fault,
or break in the Earth's crust
across which there has been
relative movement, in which
rocks of lower stratigraphic
position are pushed up and over
higher strata.
 They are often recognized
because they place older rocks
above younger. Thrust faults are
the result of
compressional forces.
[B] On the basis of the amount of
dip of the fault
1) High angle faults
 These are those faults in which
the fault plane dips steeply, at
angles more than 45’, as generally
happens in normal faults.
2) Low angle fault
 These are those faults in which
the fault planes dips gently, at
angles less than 45’, as generally
happens in thrust faults.
[C] On the basis of Attitude of
the fold
1) Strike fault
 A strike fault is that in
which the strike direction
of the adjacent beds i.e.
the fault strikes along the
strike of the beds.
2) Dip fault
 A dip fault is that in which
the strike of the fault is
normal (perpendicular) to
the strike of the adjacent
beds.
3) Oblique fault
 An oblique fault is that in
which the fault plane
strikes obliquely
(diagonally) to the adjacent
beds, i.e. fault plane strike
neither parallely nor
normally to the adjacent
beds.