The document discusses mass wasting and its controlling factors. Mass wasting is the downslope movement of weathered material under gravity. The key controlling factors are: 1) Slope angle, as increased slope angle increases the tendency for material to slide downslope. 2) The role of water, as water reduces friction and the angle of repose, increasing flow. Saturated materials flow like fluids while dry materials resist movement. 3) The presence of clays, as expansive clays that absorb water can cause soils to expand and contract, increasing mass wasting risks.

1. MASS WASTING
A presentation reported by Group 1

2. LEARNING OBJECTIVES
•Identify the controls and triggers of mass
wasting; and
•Distinguish between different mass wasting
processes

3. What is Mass Wasting?
REVIEW

5. Mass Wasting
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.

6. Mass Wasting
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.

7. Mass Wasting
CONTROLLING FACTORS
IN MASS WASTING

8. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.

9. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
All forces resisting movement
downslope can be grouped under
the term shear strength. This is
controlled by frictional resistance
and cohesion of particles in an
object, amount of pore pressure
of water, and anchoring effect of
plant roots. When shear stress is
greater than shear strength,
downslope occurs.

10. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
All forces resisting movement
downslope can be grouped under
the term shear strength. This is
controlled by frictional resistance
and cohesion of particles in an
object, amount of pore pressure
of water, and anchoring effect of
plant roots. When shear stress is
greater than shear strength,
downslope occurs.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface

11. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.

12. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.
• Slightly wet unconsolidated materials exhibit a very high
angle of repose because surface tension between the water
and the grains tends to hold the grains in place.

13. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.
• Slightly wet unconsolidated materials exhibit a very high
angle of repose because surface tension between the water
and the grains tends to hold the grains in place.
• When the material becomes saturated with water, the angle of repose
is reduced to very small values and the material tends to flow like a
fluid. This is because the water gets between the grains and eliminates
grain to grain frictional contact.

14. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.
• Slightly wet unconsolidated materials exhibit a very high
angle of repose because surface tension between the water
and the grains tends to hold the grains in place.
• When the material becomes saturated with water, the angle of repose
is reduced to very small values and the material tends to flow like a
fluid. This is because the water gets between the grains and eliminates
grain to grain frictional contact.
• Expansive and hydrocompacting soils – contain a high proportion of
smectite or montmorillonite which expand when wet and shrink when
they dry out.
3.) Presence of clays

15. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.
• Slightly wet unconsolidated materials exhibit a very high
angle of repose because surface tension between the water
and the grains tends to hold the grains in place.
• When the material becomes saturated with water, the angle of repose
is reduced to very small values and the material tends to flow like a
fluid. This is because the water gets between the grains and eliminates
grain to grain frictional contact.
• Expansive and hydrocompacting soils – contain a high proportion of
smectite or montmorillonite which expand when wet and shrink when
they dry out.
• Sensitive soils - Clays in some soils rearrange themselves after
dissolution of salts in the pore spaces. Clay minerals line up with one
another and the pore space reduced.
3.) Presence of clays

16. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.
• Slightly wet unconsolidated materials exhibit a very high
angle of repose because surface tension between the water
and the grains tends to hold the grains in place.
• When the material becomes saturated with water, the angle of repose
is reduced to very small values and the material tends to flow like a
fluid. This is because the water gets between the grains and eliminates
grain to grain frictional contact.
• Sensitive soils - Clays in some soils rearrange themselves after
dissolution of salts in the pore spaces. Clay minerals line up with one
another and the pore space reduced.
3.) Presence of clays
• Quick clays - Water- saturated clays that spontaneously liquefy when
disturbed.

17. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.
• Slightly wet unconsolidated materials exhibit a very high
angle of repose because surface tension between the water
and the grains tends to hold the grains in place.
• When the material becomes saturated with water, the angle of repose
is reduced to very small values and the material tends to flow like a
fluid. This is because the water gets between the grains and eliminates
grain to grain frictional contact.
• Sensitive soils - Clays in some soils rearrange themselves after
dissolution of salts in the pore spaces. Clay minerals line up with one
another and the pore space reduced.
3.) Presence of clays
• Quick clays - Water- saturated clays that spontaneously liquefy when
disturbed.
4.) Weak materials and
structures
• Become slippage surfaces if weight is added or support is removed
(bedding planes, weak layers, joints, and fractures, foliation
planes)

18. Mass Wasting
CONTROLLING FACTORS IN MASS WASTING
• Process whereby weathered material is moved
downslope under the immediate influence of gravity.
• Slope Angle and Angle of Repose (the steepest angle
that can be assumed by loose fragments on a slope
without downslope movement) are strongly related to
rates of mass wasting.
1.) Slope Angle
• Component of gravity perpendicular to
the slope which helps hold the object in
place.
• Component of gravity parallel to the
slope which causes shear stress and
helps move objects downslope.
• As the slope increases, the slope-parallel
component increases while the slope
perpendicular component decreases.
Thus, the tendency to slide down the
slope becomes greater.
2.) Role of Water
• Water has the ability to change the angle of repose (the
steepest slope at which a pile of unconsolidated grains
remain stable).
• Addition of water from rainfall or snowmelt adds
weight to the slope.
• Water can reduce the friction along a sliding surface
• The slope angle of a pile of dry, unconsolidated grains will be
defined by the angle of repose. With larger grains, the angle of
repose for dry materials rises, yet it typically ranges between
30 and 45 degrees.
• Slightly wet unconsolidated materials exhibit a very high
angle of repose because surface tension between the water
and the grains tends to hold the grains in place.
• When the material becomes saturated with water, the angle of repose
is reduced to very small values and the material tends to flow like a
fluid. This is because the water gets between the grains and eliminates
grain to grain frictional contact.
• Sensitive soils - Clays in some soils rearrange themselves after
dissolution of salts in the pore spaces. Clay minerals line up with one
another and the pore space reduced.
3.) Presence of clays
• Quick clays - Water- saturated clays that spontaneously liquefy when
disturbed.
4.) Weak materials and
structures
• Become slippage surfaces if weight is added or support is removed
(bedding planes, weak layers, joints, and fractures, foliation
planes)
MASS
WASTING
PROCESSES

19. MASS WASTING PROCESSES
• Slope Failures - Sudden failure of the slope resulting in
transport of debris downhill by rolling, sliding and
slumping.

20. MASS WASTING PROCESSES
• Slump - A type of slide where in downward rotation of
rock or regolith occurs along a curved surface.

21. MASS WASTING PROCESSES
• Rock fall and debris fall - Free falling of dislodged bodies
of rocks or a mixture of rock, regolith, and soil in the
case of debris fall.

22. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.

23. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.
TWO TYPES SEDIMENT FLOW
• Granular flow - Contains
low amounts of water, 0-
20% water; fluid-like
behaviour is possible by
mixing with air (creep,
earth flow, grain flow,
debris avalanche).
• Slurry flow - Water-
saturated flow which
contains 20-40% water;
above 40% water
content, slurry flows
grade into streams (
solifluction, debris flow,
mud flow)

24. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.
TWO TYPES SEDIMENT FLOW
• Granular flow - Contains
low amounts of water, 0-
20% water; fluid-like
behaviour is possible by
mixing with air (creep,
earth flow, grain flow,
debris avalanche).
• Solifluction - A common wherever water cannot
escape from the saturated surface layer by
infiltrating to deeper levels; creates distinctive
features: lones and sheets of debris.
TYPES OF SLURRY FLOW

25. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.
TWO TYPES SEDIMENT FLOW
• Granular flow - Contains
low amounts of water, 0-
20% water; fluid-like
behaviour is possible by
mixing with air (creep,
earth flow, grain flow,
debris avalanche).
Debris Flow
• Results from heavy rains causing soil and regolith to be saturated with
water.
• Commonly have a tongue-like structure
• Composed mostly of volcanic materials on the flanks of volcanoes are
called lahars.
• Debris flow contains 10-25% water, hyperconcentrated stream flow has
25-40% water, and mudflow is restricted to flows composed dominantly of
mud.
TYPES OF SLURRY FLOW

26. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.
TWO TYPES SEDIMENT FLOW
• Granular flow - Contains
low amounts of water, 0-
20% water; fluid-like
behaviour is possible by
mixing with air (creep,
earth flow, grain flow,
debris avalanche).
TYPES OF SLURRY FLOW
Mud Flow
• Highly fluid, high velocity mixtures of sediments and
water;
• Can start as a muddy stream that becomes a moving
dam of mud and rubble;
• Differs flow in that fine-grained material
predominant.

27. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.
TWO TYPES SEDIMENT FLOW
• Granular flow - Contains
low amounts of water, 0-
20% water; fluid-like
behaviour is possible by
mixing with air (creep,
earth flow, grain flow,
debris avalanche).
TYPES OF SLURRY FLOW
GRANULAR FLOW
Creep
• Slowest type of mass wasting requiring several years of gradual movement to have a
pronounced effect on the slope;
• Evidence often seen in bent trees, offset in roads and fences, inclined utility poles.
• Creep occurs regolith alternately expands and contracts in response to freezing and thawing,
wetting and drying or warming and cooling.

28. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.
TWO TYPES SEDIMENT FLOW
• Granular flow - Contains
low amounts of water, 0-
20% water; fluid-like
behaviour is possible by
mixing with air (creep,
earth flow, grain flow,
debris avalanche).
TYPES OF SLURRY FLOW
Creep
• Slowest type of mass wasting requiring several years of gradual movement to have a
pronounced effect on the slope;
• Evidence often seen in bent trees, offset in roads and fences, inclined utility poles.
• Creep occurs regolith alternately expands and contracts in response to freezing and thawing,
wetting and drying or warming and cooling.
Earth Flow
• Involves fine-grained material such as clay and silt and
usually associated with heavy rain or snowmelt; tend to
be narrow tongue-like features that begin at a scarp or
cliff
GRANULAR FLOW

29. MASS WASTING PROCESSES
• Sediment flow - Material flow downhill mixed with water
or air.
TWO TYPES SEDIMENT FLOW
• Granular flow - Contains
low amounts of water, 0-
20% water; fluid-like
behaviour is possible by
mixing with air (creep,
earth flow, grain flow,
debris avalanche).
TYPES OF SLURRY FLOW
GRANULAR FLOW
Creep
• Slowest type of mass wasting requiring several years of
gradual movement to have a pronounced effect on the
slope;
• Evidence often seen in bent trees, offset in roads and
fences, inclined utility poles.
• Creep occurs regolith alternately expands and contracts
in response to freezing and thawing, wetting and drying
or warming and cooling.
Earth Flow
• Involves fine-grained material such as clay and silt and
usually associated with heavy rain or snowmelt; tend to
be narrow tongue-like features that begin at a scarp or
cliff
Grain Flow
• Forms in dry or nearly dry granular sediment with air
filling the pore spaces such as sand flowing down the
dune face.

30. TYPES OF SLURRY FLOW
GRANULAR FLOW
Creep
• Slowest type of mass wasting requiring several years of
gradual movement to have a pronounced effect on the
slope;
• Evidence often seen in bent trees, offset in roads and
fences, inclined utility poles.
• Creep occurs regolith alternately expands and contracts
in response to freezing and thawing, wetting and drying
or warming and cooling.
Earth Flow
• Involves fine-grained material such as clay and silt and
usually associated with heavy rain or snowmelt; tend to
be narrow tongue-like features that begin at a scarp or
cliff
Grain Flow
• Forms in dry or nearly dry granular sediment with air
filling the pore spaces such as sand flowing down the
dune face.
Debris Avalanche
• Forms in dry or nearly dry granular sediment with air
filling the pore spaces such as sand flowing down the
dune face.

31. Creep
• Slowest type of mass wasting requiring several years of
gradual movement to have a pronounced effect on the
slope;
• Evidence often seen in bent trees, offset in roads and
fences, inclined utility poles.
• Creep occurs regolith alternately expands and contracts
in response to freezing and thawing, wetting and drying
or warming and cooling.
Earth Flow
• Involves fine-grained material such as clay and silt and
usually associated with heavy rain or snowmelt; tend to
be narrow tongue-like features that begin at a scarp or
cliff
Grain Flow
• Forms in dry or nearly dry granular sediment with air
filling the pore spaces such as sand flowing down the
dune face.
Debris Avalanche
• Forms in dry or nearly dry granular sediment with air
filling the pore spaces such as sand flowing down the
dune face.
Schematic Diagram of a Slump

32. TYPES OF SLURRY FLOW
GRANULAR FLOW
Creep
• Slowest type of mass wasting requiring several years of
gradual movement to have a pronounced effect on the
slope;
• Evidence often seen in bent trees, offset in roads and
fences, inclined utility poles.
• Creep occurs regolith alternately expands and contracts
in response to freezing and thawing, wetting and drying
or warming and cooling.
Earth Flow
• Involves fine-grained material such as clay and silt and
usually associated with heavy rain or snowmelt; tend to
be narrow tongue-like features that begin at a scarp or
cliff
Grain Flow
• Forms in dry or nearly dry granular sediment with air
filling the pore spaces such as sand flowing down the
dune face.
Debris Avalanche
• Forms in dry or nearly dry granular sediment with air
filling the pore spaces such as sand flowing down the
dune face.
Schematic Diagram of a Slump
Subaqueous mass wasting
• Subaqueous mass movement occurs on
slopes in the ocean basins. This may occur
as a result of an earthquake or due to an
over-accumulation of sediment on slope
or submarine canyon

33. Subaqueous mass wasting
Three Types
Submarine
slumps
similar to
slumps on
land
Submarine
debris flow
similar to
debris flow
on land
Turbidity current
sediment moves as
a turbulent cloud

34. Events that trigger mass wasting
processes

35. Events that trigger mass wasting
processes
Shocks and
vibrations
Earthquakes and
minor shocks such
as those produced
by heavy trucks on
the road , man-
made explosions.
Slope
modification
Creating artificially
steep slope so it is
no longer at the
angle of repose.
Undercutting
Due to streams
eroding banks of
surf action
undercutting a
slope.

36. Events that trigger mass wasting
processes
Shocks and
vibrations
Earthquakes and
minor shocks such
as those produced
by heavy trucks on
the road , man-
made explosions.
Slope
modification
Creating artificially
steep slope so it is
no longer at the
angle of repose.
Undercutting
Due to streams
eroding banks of
surf action
undercutting a
slope.
Changes in
hydrologic
Characteristics
Heavy rains lead to
water-saturated
regolith increasing it’s
weight, reducing grain
to grain contact and
angel of repose.
Changes in slope
strength
Weathering weakens the
rock and leads to slope
failure; vegetation holds
soil in place and slows
the influx of water; tree
roots strengthen slope by
holding the ground
together.
Volcanic
eruptions
Produce shocks; may
produce large volumes
of water from melting
of glaciers during
eruption , resulting to
mudflows and debris
flows.

37. Landslide Warning
Signs

38. Landslide Warning Signs
• Springs, seeps, or saturated ground in areas that have not typically been wet before.
• New cracks or unusual bulges in the ground, street pavements or sidewalks.
• Soil moving away from foundations.
• Ancillary structures such as decks and patios tilting and/or moving relative to the main
house.
• Tilting or cracking of concrete floors and foundations.
• Broken water lines and other underground utilities.
• Leaning telephone poles, trees, retaining walls or fences.
• Offset fence lines.
• Sunken or down-dropped road beds.
• Rapid increase in creek water levels, possibly accompanied by increased turbidity (soil
content).
• Sudden decrease in creek water levels though rain is still falling or just recently stopped.
• Sticking doors and windows, and visible open spaces indicating jambs and frames out of
plumb.
• A faint rumbling sound that increases in volume is noticeable as the landslide nears.
• Unusual sounds, such as trees cracking or boulders knocking together, might indicate moving
debris.

39. How landslide hazard can
be reduced

40. How landslide hazard can be reduced
Hazard zone mapping. One of the most important step in hazard
mitigation is the production of a landslide hazard map. These
maps should serve to reduce hazard by keeping away from the
most vulnerable slopes.
An example of a
Hazard Map

41. How landslide hazard can be reduced
Proper land
• Areas covered by degraded natural vegetation in the upper slopes
should be afforested and existing natural vegetation preserved.
• Developmental activity should be taken up only after a detailed
study of the area.
• Proper care to be taken to avoid blockage of natural drainage.
• Mandatory total avoidance of settlement in the risk zone.
• Building codes that limit the steepness of slope when building in
hilly areas.
• Relocate settlements and infrastructures that are in the possible
path of a landslide.

42. How landslide hazard can be reduced
Engineering mitigation techniques
• Anchoring the footings of a structure in solid bedrock. This is a
simple mitigation method for creep.
• Drainage systems (e.g. installation hydrauger holes, drainage
ditches, or planting vegetation) that drain water from the
surface and/or subsurface.
• Buttress fills and retaining devices to stabilize slope. Example
includes retaining walls, shotcrete, metal mesh, and
rockbolts.
• Building deflection walls to send flows around a structure.

43. THANK YOU

44. Group 1 Members
- Aiza Abegail Etao Puscablo
- Anna Trisha Marie Manocasi
- Arvielle Jane Villanueva
- Bianca Denise Real
- Chris Lawrence Libarios
- Gian Piamonte
- Harrold Managbanag
- Janine Jiya Jeloca
- John Loyd Nigos Amaro
- Klyza Maye Ceballos
- Sam Gabrielle Gornez
- Theophanie Natalie Salcedo Caisic