I made this for my environment project - Mass Wasting. Thanks Pranav, Zubin and Adhish

1. Adhish Luitel Prasil Koirala
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Pranav Bhandari Zubin Raj Bhandary
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2.  Definition: Geomorphic process by which soil, regolith,
and rock move down slope under the force of gravity.
 Mass wasting occurs on both terrestrial and submarine slopes, and
has been observed on Earth, Mars, Venus, and Jupiter's moon.
 When the gravitational force acting on a slope exceeds its resisting
force, slope failure (mass wasting) occurs. The slope material's
strength and cohesion and the amount of internal friction between
material help maintain the slope's stability and are known
collectively as the slope's shear strength. The steepest angle that a
cohesionless slope can maintain without losing its stability is known
as its angle of repose. When a slope possesses this angle, its shear
strength perfectly counterbalances the force of gravity acting upon
it.

3. Mass Wasting

4.  Types of mass movement are distinguished based on how
the soil, regolith or rock moves down slope as a whole. It is
basically categorized into 5 basic types:
▪ Creeps
▪ Landslides
▪ Flows
▪ Topples
▪ Slump
Home > Types of Mass Movement

5.  Types of mass movement are distinguished based on how
the soil, regolith or rock moves down slope as a whole. It is
basically categorizedof smallbasic types:of soil or rock in
+ It is the combination into 5 movements
different directions over time are directed by gravity gradually
▪ Creeps
downslope.
▪ Landslides
+ The steeper the slope, the faster the creep. The creep makes trees
▪ shrubs
and Flowscurve to maintain their perpendicularity, and they can
trigger landslides if they lose their root footing.
▪ Topples
▪ Slump
+ The surface soil can migrate under the influence of cycles of
freezing and thawing, or hot and cold temperatures, inching its
way towards the bottom of the slope forming terracettes. This
happens at a rate that is not noticeable to the naked eye.
Home > Types of Mass Movement >Creeps

6.  Types of mass movement are distinguished based on how
the soil, regolith or rock moves down slope as a whole. It is
basically categorized into 5 basic types: a well-defined
+ Where the mass movement has
▪ Creeps plane of sliding, it is called a landslide. This
zone or
▪ Landslides slides, slumps and sturzstroms.
includes rock
▪ Flows also one of the common classification of mass
+ It is
▪ Topples
wasting
▪ Slump
Home > Types of Mass Movement > Landslides

7.  Types of mass movement are distinguished based on how
the soil, regolith or rock moves down slope as a whole. It is
basically categorized into 5regolith that more
+ Movement of soil and basic types:
▪ Creeps fluid behavior is called a flow.
resembles
▪ Landslides
+ These include avalanches, mudflows, debris
▪ Flows flow, lahars and sturzstroms.
flows, earth
▪ Topples
+ Water, air and ice are often involved in enabling
▪ Slump
fluidlike motion of the material.
Home > Types of Mass Movement > Flows

8.  Types of mass movement are distinguished based on how
the soil, regolith or rock moves down slope as a whole. It is
basically categorized into 5 basic types:
▪ Creeps
Topples are instances when blocks of rock
▪ Landslides
pivot and fall away from a slope.
▪ Flows
▪ Topples
▪ Slump
Home > Types of Mass Movement > Topples

9.  Types of mass movement are distinguished based on how
the soil, regolith or rock moves down slope as a whole. It is
basically categorized into 5 basic types:
A slipping of coherent rock material along the curved
▪ Creeps
surface of a decline. Slumps involve a mass of soil or
▪ Landslides
other material sliding along a curved surface (shaped
▪ Flows
like a spoon). It forms a small, crescent-shaped cliff, or
abrupt scarp at the top end of the slope. There can be
▪ Topples
more than one scarp down the slope.
▪ Slump
Home > Types of Mass Movement > Slump

11.  Gravitational pull of the earth
 seismic shaking
 increased overburden from structures
 increased soil moisture
 reduction of roots holding the soil to bedrock
 undercutting of the slope by excavation or erosion
 weathering by frost heave
 Bioturbation
 Earthquake - Violent shaking due to an earthquake can cause unstable
slopes to collapse
 Quick Clay- Soil liquefaction causes land to collapse
… > Factors triggering mass wasting

12. ```
Mass movements affects the following elements:
 The topography of the earth's surface, particularly
the morphologies of mountain and valley systems
 The quality of rivers and streams and groundwater flow
 The forests that cover much of the earth's sub aerial
surface
… > Effects of mass wasting

13.  Cause floods by damming up bodies of water and
result to huge loss of lives and property.
 Affect the agricultural lands
 Loss of industrial productivity because of
interruption of transportation system by landslides.
 Increase the number of environmental refugees.

14. Mass wasting causing Avalanche as an
road damage example of mass
wasting

15.  In a flow the material moved is not coherent but moves in a
more chaotic, disorganized fashion.
 It flows with mixing with particles within the flowing mass as
a fluid flows. Snow avalanches are one kind of flows.
 Where soil Is the flowing material these flos are described as
mudflows. When a flow involves a wide variety of material is
known as a debris avalanche.

16. Avalanche

17. + Mass movement can occur on a variety of scales and at a variety of rates. They may
involve a few cubic meters of material or more than a million cubic material.
+ In the most rapid mass movements which include most rock falls and avalanches
and mudflow s, materials can travel at speeds of hundreds of kilometers per hour.
+ There is little time for people to react once these events start and such events are
the cause of the greatest proportion of mass movement casualties. They also cause
extensive damage to buildings.

18.  Landslides : can also be the cause of floods. A
stream in the process of cutting a valley may cause
unstable slopes. Landslides into the valley can dam
up the stream flowing through it, creating a natural
reservoir. The filling of the reservoir makes the are
behind the dam uninhabitable

20.  Many types of construction lead to over steeping of slopes.
 Removal of material at the bottom of a hill may leave large rock
masses unsupported.
 Building of houses on an unstable slope can lead to excess
pressure being put on the slope.
 Planting of vegetation like trees can reduce the risk of unstable
slopes and slides.
 Irrigation and use of septic tanks increase the flushing of water
through soils and sediments.
 Artificial reservoirs can cause earthquakes as well as landslides.
 As the volume of the reservoir increases in volume, pressure
exerted on the rocks along the reservoirs increases and the
strength of the rocks also decreases.
 This may cause the dam to collapse.

22.  Slope reduction
 Retention Structures
 Fluid removal
 Other slope stabilizing method
 Recognizing the hazard
 Landslide Warnings

23.  Reducing the steepness of the slope
 Strengthening the slope by providing supporting materials at the base of
the slope
 Reducing the load on the slope by removing all the large rocks or soil at
the higher parts of the slope
The measures that should be taken
depend upon the stability of the slope.
A highly unstable slope might require
all these preventive measures to be
taken at once. These steps should be
carried out cautiously. For example, if
earthmoving equipment is used the
load of the equipment or the vibration
caused by it might trigger the
landslide

24.  The groundcover should be increased by the means of plantation. A plant
that grows quick and that has a strong root system is preferred.
 Strong walls can be constructed on the basis of the magnitude of force
that could act on the wall.
The success rate of these kinds
of structures has generally been
low. Generally, high and thin
walls have not been successful.

25.  Water is the most significant cause of mass movement.
 One of the basic ways of preventing landslide is to reduce the water
pressure in the slope. Subsurface drainage can also be a method.
Any kind of moisture
removal system is highly
encouraged due to
which it become difficult
for the rocks and soil to
slide off as the frictional
resistance to sliding
increases.

26.  Vertical piles are placed on the base of the slope where the particles in
the slope are solid.
This is not to be used anywhere. If the soil
contains more fluid, the soil will just come The use of rock bolts to stabilize rocky
out or flow within the vertical piles. It is also slopes and rock slides has had a greater
not applicable in highly steep slope. success. Rock bolts have been used in
Generally, this technique is not very tunneling and mining. Sometimes the
successful. process of driving giant steel bolts in to
the stable rocks below the slip planes is
also used. This works best in low angle
slopes.

27.  Basic climatic feature, topography and geology cause mass movement in a
place; they are independent of any human activities.
 Mass movements tend to recur in the same place where they commonly
occur.
 It is very easy to recognize past rock falls in a vegetated area. Large rocks are
not suitable in a vegetated area and remain barren. Lack of vegetation might
also lead to past debris avalanche and slides. These kinds of factors lead the
landscape to slope instability. .
 When there are small slips in the soil. The trunk of the tress grows a bit
slanted but later vertical growth continues. If the gradual movement of soil is
prolonged then the tree trunks maybe curved.
 Slanted utility poles and fences, tilting over of object can also act as an
indicator of soil movement

28.  Landslide warning system was developed by U.S. geological survey after
the rain triggered landslide in San Francisco Bay in 1982. The basis of the
warning system was to establish a quantitative relationship among
rainfall intensity, storm duration, and a variety of slope and soil
characteristics relating to slope instability like slope angle, fluid pressure
and so on.
 These relationships are established using factual data of past landslides.
It became possible to estimate the limits of storm intensity and duration
which when crossed might result in landslide, given it was known how
saturated the ground was due to the recent precipitation.
The system though incomplete
was tested in February 1986. Of
the ten landslides predicted, eight
took place when forecasted.

29. Landslide warning

31. Or need more information?
Available Topics..
•Mass Wasting
•Factors causing it
•Preventive Measures
Bibliography:
www.wikipedia.com
National Geographic
Google Images
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