Landslides: Types and Causes
Summary
TLDRThis educational video delves into the hazards of landslides, a recurring phenomenon exacerbated by factors like topography, rainfall, and human activities. It highlights the significant impact on agriculture, infrastructure, and human life, with an annual cost of nearly 2 billion rupees. The script explains the different types of landslides, including falls, topples, slides, and spreads, and discusses the causes, such as slope failure, deforestation, and unscientific development, emphasizing the critical role of human interference in destabilizing slopes.
Takeaways
- 🏔 Landslides are a serious geological hazard, particularly in areas with rugged topography and heavy rainfall.
- 🌧 Landslides are a chronic problem in hilly regions due to factors like development activities and exploitation of natural resources.
- 📈 The monsoon season is a peak time for landslides, causing disruptions in communication, property loss, and sometimes loss of life.
- 🗺 The landslide hazard map of India shows high risk in the Himalayan terrain and northeastern hill ranges, with moderate risk in the western ghats.
- 💔 Landslides have a significant impact on agriculture, forests, infrastructure, and can lead to substantial monetary losses for the nation.
- 🚨 Early warning signs of landslides include tilted structures, cracks in foundations, and changes in water flow or falling debris.
- 📚 Landslides involve the downward and outward movement of soil or rock mass due to gravity and can be categorized into different types like falls, topples, slides, and spreads.
- 🔍 Key terms in landslide studies include crown, flanks, head, foot, main scarp, and surface of rupture, which help in understanding the mechanics of landslides.
- 📉 The types of landslides range from rock falls and debris slides to complex landslides that involve a combination of different movements.
- 🌳 Causes of landslides include slope failure, deforestation, hydrostatic pressure, earthquakes, intense rainfall, and human activities such as construction and land use changes.
- ⚠️ Human interference, such as improper construction practices and deforestation, significantly contributes to the instability of slopes and the occurrence of landslides.
Q & A
What is a landslide?
-A landslide is a serious geological hazard involving the downward and outward movement of soil or rock mass under the influence of gravity, often triggered by factors such as heavy rainfall, slope failure, or human activities.
Why are landslides particularly common during the monsoon season?
-Landslides are particularly common during the monsoon season due to heavy and prolonged rainfall, which increases the water content in the soil, reducing its stability and leading to slope failure.
What are the areas in India most prone to landslides according to the landslide hazard map?
-According to the landslide hazard map, the Himalayan terrain, northeastern hill ranges, and western ghats are the areas most prone to landslides in India.
What are the socioeconomic impacts of landslides?
-Landslides can cause substantial damage to agriculture, forests, roads, and telecommunication infrastructure. They can also result in injury, loss of life, and property damage, leading to significant monetary losses for the nation.
What are some early warning signs of a potential landslide?
-Early warning signs of a potential landslide include tilted telephone poles or trees, cracks in foundations or roads, and sudden changes in the flow of water or falling of stones from hill slopes.
What types of landslides are mentioned in the script?
-The script mentions several types of landslides, including rock fall, debris fall, soil fall, rock topple, debris topple, soil topple, rotational slides, translational slides, and complex landslides.
How do rotational slides differ from translational slides?
-Rotational slides involve movement on a circular or near-circular surface of failure and are characterized by a scarp at the head. Translational slides, on the other hand, are non-rotational and involve mass movement on more or less planar surfaces.
What is the role of human activities in causing landslides?
-Human activities such as deforestation, unscientific construction practices, and developmental projects like road building can destabilize slopes and contribute to landslides by altering the natural landscape and increasing the load on hill slopes.
How do earthquakes contribute to landslides?
-Earthquakes can contribute to landslides by reducing the shearing resistance along fracture zones or joint planes, making loose and unconsolidated sediments on steep slopes more vulnerable to movement.
What is the significance of the surface of rupture in understanding landslides?
-The surface of rupture is significant in understanding landslides as it represents the plane along which the soil or rock mass moves. Identifying this surface helps in assessing the type and potential movement of a landslide.
Outlines
🌧️ Landslides: Causes and Impacts
The first paragraph introduces the topic of landslides, highlighting them as a serious and recurring natural hazard. It mentions the primary causes such as rugged topography, heavy rainfall, and human activities like development and exploitation of natural resources. The paragraph also discusses the specific regions in India where landslides are common and the severe impacts they have on agriculture, infrastructure, human life, and the environment. The annual monetary loss due to landslides is noted to be nearly 2 billion rupees, emphasizing the socioeconomic and human misery caused by these events.
🏔️ Understanding Landslide Terminology and Types
This paragraph delves into the technical aspects of landslides, explaining the terminology used to describe different parts of a landslide, such as the crown, flanks, head, toe, and main body. It then categorizes landslides into types based on their movement and characteristics, including falls, topples, slides, and flows. Each type is further described with its specific features and examples, providing a comprehensive understanding of the various forms landslides can take.
🪨 Causes of Landslides: Natural and Anthropogenic Factors
The third paragraph focuses on the causes of landslides, which range from natural factors like slope failure and intense rainfall to human activities such as deforestation and unscientific construction practices. It explains how steep slopes, high rainfall, and poor land use changes can increase the likelihood of landslides. The paragraph also touches on the role of hydrostatic pressure, erosion, and earthquake shocks in triggering landslides, and how human interference, such as the use of explosives and improper construction, can exacerbate the problem.
🛠️ Human Activities and Their Contribution to Landslide Instability
The final paragraph emphasizes the significant role of human activities in causing landslides. It discusses how developmental and engineering activities, such as construction and hill cutting, can destabilize slopes and lead to landslides. The paragraph also mentions the consequences of overloading slopes, improper water management, and the lack of engineering considerations in construction projects. It concludes by reiterating the importance of understanding landslides and their causes, particularly the impact of human interference.
Mindmap
Keywords
💡Landslide
💡Topography
💡Monsoon
💡Natural Resources Exploitation
💡Landslide Hazard Map
💡Ecosystem
💡Socioeconomic Structure
💡Surface Rupture
💡Deforestation
💡Hydrostatic Pressure
💡Development and Engineering Activities
Highlights
Landslides are a serious geological hazard with annual and recurring occurrences.
Landslides are primarily caused by rugged topography, unfavorable hill slopes, heavy rainfall, and exploitation of natural resources.
The monsoon season particularly exacerbates landslide occurrences, impacting communication and causing loss of life and property.
The landslide hazard map of India shows varying degrees of risk across different regions.
Landslides cause substantial damage to agriculture, forests, roads, telecommunication, and engineering structures.
The economic impact of landslides in India is significant, with an estimated annual loss of nearly 2 billion rupees.
Landslides not only disrupt the socioeconomic structure of regions but also cause human misery.
Landslides are categorized into different types such as falls, topples, slides, spreads, and flows.
The movement of landslides can range from soil creep to huge landslides, with varying terminologies used to describe them.
Translational slides are non-rotational block slides involving mass movement on planar surfaces.
Spread landslides are caused by liquefaction where saturated sediments transform into a liquid state.
Flow landslides involve rapid movement of material as a viscous mass, such as debris flows or mud flows.
Complex landslides involve a combination of different types of movements.
Causes of landslides include slope failure, deforestation, hydrostatic pressure, earthquakes, and development activities.
Human interference, such as construction and land use changes, significantly contributes to landslide occurrences.
The importance of understanding landslide terminologies and types for effective disaster management.
The role of early warning signs like tilted poles, cracks in foundations, and changes in water flow for predicting landslides.
Transcripts
so
[Music]
[Music]
dear learners welcome
today we'll discuss about the landslides
stripes and causes
landslide is a serious jollical hazard
it's an annual and recurring phenomena
it is a major chronic problem primarily
because
of the rugged topography
unfavorable hill slopes
heavy and prolonged rainfall
development activities and exploitation
of natural resources in the hilly region
have further aggravated this problem
it is particularly common during the
monsoon affecting communication
loss of property
and sometimes even the human life
it also damages natural resources and
disturb the ecosystem and involvement
well let's see the
landslide hazard map of india
it shows that in the himalayan terrain
it is very high
and it is high in the northeastern hill
ranges
and
moderate in the western ghat and il
greece severity it comes down from the
himalayan terrain from the northeastern
religion then western heart nil greece
and eastern ghat and the vindhyan we all
know about the effect of the landslide
it causes substantial damage to
agriculture and forest wealth
roads telecommunication and major
engineering structures it has great
impact on injury and loss of life and
damage to the properties it also causes
blocking of the rivers channels thereby
forming a huge lakes which when burst
creates flash flood causing much heavy
losses
the nation suffers heavy monetary loss
every year because of the landslides
it is enormous when cumulative figures
are taken
you will be surprised that total
estimate cost for loss of property is
nearly 2 billion
rupees per annum in this landslide
incidences
thus this landslide hazards
have very serious impact not only on
socioeconomic structure of the region
but also in disruption
a complete misery to the human life
you see
any landslide is not a disaster
landscape basically the hazard
but when this landslide affect any loss
property
or the life then it becomes a disaster
let's see the effect and sign of the
landslides
well
tilted telephone poles
retaining walls or sometimes trees you
see it takes a turn near the slope
cracks in the foundation can be seen
even in the houses you can the side
walls and the driveways of the houses
even the cracks are developed on the
ground and the roads
and sudden emergence or stoppage of
flowing water
or falling of stones or boulders from
the hill slopes are also the early
warning of a landslide
now let's understand the landslide in
fact landslides are downward and outward
moment
of soil or rock mass
that may be set off by one or more
causes under the influence of gravity
whereas people have used different terms
for landslides
such as mass wasting
mass movement
slope failure and slope movement
mass movements can range in magnitude
from soil creep to huge landslides now
there are very terminologies that we use
in case of landslides
let's see crown
the top portion of a landslide is a
crown then flanks both sides that refers
to the portion of the slides with un
displaced material
adjacent to the sides of the rupture
surface
that head of the slide is the upper part
of the landslide along the contact
between the displaced material and the
main scarp and foot is the portion of
the landslide that has moved beyond the
toe of the surface of rupture that
overlap the original ground surface and
main body is the main part of the
displaced material
of the landslide that overlaps the
surface of rupture between the main scar
and toe of the surface of rupture main
scarp is a steep surface on the
undisturbed ground of the upper edge of
the landslide which is caused by the
movement of
displaced material away from the
undisturbed ground
it is visible part of the surface of the
rupture
a minus curve is a steep slope on
displaced material which is produced by
the differential movement within the
displaced material
surface absorption surface that forms
lower boundary that displace the
material below the original ground
surface is the surface of rupture and
this is very important to study
or to know what is the surface of
rupture then accumulation it is a volume
of the displaced material which has
fallen from the top and has been
accumulated on the ground surface well
so toe is the lowest usually curved
margin of the displaced material of a
landslide it is the most distinct part
from the main scarp now let let's see
the types of landslide the first
category is the false
it refers to the abrupt movement of the
slope material that becomes detached
from steep slope or cliffs
most of the movement occur by free fall
or by rolling or bouncing
depending upon the type of slope
material it may be called as rock fall
debris fall or soil fall
you see when we talk about rock fall it
is a mass of the rock of any size
detached from a steep slope or cliff
that descend mostly through the air by
free falling and when we talk of the
debris fall it is the same as rockfall
but the material is smaller it is in
forms of debris
likewise the soil fall it is the same as
the rockfall but the material involved
in the soil
then we have the topple nest category is
topples it refers to those blocks of
frog that tilt or rotate forward on a
pivot or hinge
again it can be called as rock topple
debris stopple or soil tupple depending
on the type of the material so rock
topple forward rotation of a unit under
the action of gravity of the other
forces that created by the adjacent unit
or by
fluid in cracks
now next category the slides it refers
to the movement caused by the finite
shear failure along one or more surface
of the rupture which are visible or
whose presence may reasonably be
inferred very slow movement of the slide
is called a photograph show they creep
off in lower diving valley where the
road has creeped down well creep is an
extremely slows down movement of dry
surfacial matter
movement of the soil occurs in the
region which are subjected to freeze
though conditions slides are of two
types it is rotational and translational
rotational slides refer to a failure
which involves slight movement on a
circular or near circular surface of
failure
they generally occur on slopes of
homogeneous clay shale
weathered rocks and soil
the movement is more or less rotational
about an axis parallel to the contours
of the slope such slides are
characterized by a scarf at the head
which may be nearly vertical these
slides may be single rotational multiple
rotational or successive rotational
types single rotational slides a failure
which involves
sliding movement on a circular or semi
circular failure surface and multiple
rotational slides it many for
development of rotational movements that
includes two or more slip block each
with a curved slip surface tangential to
a common generally deep seated surface
it may be super imposed or juxtaposed
now coming to successive rotational
slide
as for rotational slip
but a successive slide consists of a
assembly of individual rotational slips
down a slope often of a shallower
undulation form
translation slides
are non-rotational
block slides involving mass movement on
more or less planar surface
the movement of translation slide is
controlled by weak surfaces such as
bedding
joints foliation
faults and shear zones the slide
material may range from
unconsolidated soils to slab of the rock
and the debris and these are classified
as block slides
slab slides and debris slides depending
upon the material involved as i
mentioned block slides are translational
slides in which the moving mass consists
of a single unit of a rock block that
moves down slope
it often possesses a graven at its head
slab slide as similar as for the block
slide but is fine material
it may not possess a grab one
because it may occur on a steeper slope
then debris slide a translucent slide it
covers debris that consists of many semi
independent units of disrupt nature
which may later adopt other forms of
movement and may turn into a very rapid
form may be called as diverse avalanche
it is a slide of a block now coming to
this translational slide which are
planar
in this the rock slide it is a
translational and planar movement of
rock units usually on a steep
bedded slope
it may develop into rocks of deborah's
avalanche fall and mudslide relatively
planar movement of softened agilistic
material
moving mainly on a pronounced silicon
side shear surface it advances chiefly
by sliding in elongated form on steeper
straight slopes or low bit
numbness category
is the spread it refers to the failure
caused by the liquefaction they where
saturated and loose sediments are
transformed into liquid state
normally earthquakes are responsible for
this phenomena
well flow
it refers to a rapid movement of
material as a viscous mass
it may be called as debris flow mud flow
or rock avalanche depending upon the
nature of the material involved in the
movement debris flow it is a rapid
movement of material which consists a
high proportion of coarse fragments
other granule solids water and air it
often possesses pronounced levees and
may have a sinus ridge form on hill
slope and the fans likewise mud flow
as is same as the debris flow but is
composed of fine material as you can see
a
culvert has slipped down
in one of the reasons in the hilly well
other than this we have also complex
landslides it is a category in which
combination of two or more number of
above type of movements are involved
such as rock fall plus debris flow it
may be rock slide plus rock avalanche it
may be topple plus rock etcetera so
these are the complex landslide now let
us know what are the causes of the
landslides
it broadly it is the slope failure
deforestation
unscientific forming hydrostatic
pressure
earthquake shocks intense rainfall and
cloud bursts and the development and
engineering activities now let's see one
by one
in case of slope failure
it is generally the steeper the slope
the greater the likelihood of occurrence
of a landslide landslide is a
gravitational phenomena hence slope
angle has a direct relation with the
slope stability as the slope angle
increases the gravitational forces
increase
thereby reduces the stability slope
becomes a concern when they achieve a
critical state of natural equilibrium
it becomes more critical
when rock mass overhang
along the downslope deforestation due to
deforestation soil of the area becomes
loose and fine material is loaded thus
poor spaces are developed which during
the rains are filled with water that
acts as lubricant to induce
downhill movement of material debris etc
barren slopes are more prone to erosion
that causes landslides
and land use changes
such as conversion of vegetative slopes
into buildup area also induce landslides
now another important cause is the
intense rainfall and cloud burst very
heavy downpour of rain suddenly at one
place
high rainfall coupled with drainage
network causes weakening of the
sediments and is also responsible for
high erosion seepage weathering and
leaching that all leads to trekking
landslides it is apparent that surface
morphology and subsurface sediments play
a major role in surface runoff and heavy
seepage
joint planes and cracks in rocks
and coarse grain sediments
loose boulder beds and other such
material all favors water percolation
and that cause excessive water pressure
within the sediments it is also known as
hydrostatic pressure it ultimately
increases shear stresses and decreases
shear strength of the sediments
the pore pressure also increases due to
sudden rise in water table for one
reason or the other as a result the mass
falls down or creeps slowly depending
upon the lithology volume of mass
gradient etc no erosion it is another
important cause
it is mainly along the rivers where
river water flows towards the bend
of the river with high velocity in its
outer edge
it causes rise in water level due to
centrifugal force as gravity pulls the
water downward water currents develop a
rolling spiral velocity against the bank
that erodes away the sediments it
creates an overhanging of the sediments
which collapse due to the weight of the
rock mass
earthquake shocks is another important
cause
earthquake shocks reduces the shearing
resistance along the fracture zones or
joint planes which in turns induce
landslides
in fact loose and unconstituted
sediments on the steep slopes become
vulnerable with the earthquake tremor
and that
induced landslides on scientific farming
particularly in the hilly region
the terrace cultivation of crops like
paddy cardamon etc that all needs
standing water
and this water slowly seeps inside the
ground and super saturate the hillside
which may cause landslides
now most important is the
developmental and engineering activities
the human
the landslide problem
has further been aggravated due to the
anthropogenic activities that is the
human interference
use of high power explosive during
construction of roads
dams or bridges etc may cause shattering
of the rocks
and later during the rainy season water
within the fracture zone may cause
landslides
the human interference has contributed
significantly causes instability of the
slopes
mainly in form of hill cutting for
construction of individual houses and
urban agglomeration
in fact nowadays people are
cutting the natural hill slopes
in a table land
for construction of buildings without
considering the engineering aspect the
removal of lateral support by man's
activity
is another cause of slow failure the
overloading of the hill slope is also
responsible for landslides as you can
see here a retaining wall has been built
to save the house
but such retaining walls when made
unscientifically they get toppered
resulting into unfortunate tragedies
likewise severe water seepages from
townships or villages
if this water is not channelized
it can induce unstability of the hill
slopes
thus human interference is also one of
the major causes of the landslides
now we have just learnt
what is a landslide
and what are the types and causes
as you can see the various causes but
most important the human interference
which causes landslides most
thank you
[Music]
[Music]
you
Посмотреть больше похожих видео
HAZARDS CAUSED BY GEOLOGIC PROCESSES / EARTH AND LIFE SCIENCE / SCIENCE 11 - MELC 15
Geologic Processes and Hazards
HUMAN ACTIVITIES THAT SPEED UP OR TRIGGER LANDSLIDES / EARTH & LIFE SCIENCE / SCIENCE 11 - MELC 17
APES Topic 4.2, Soil Formation & Erosion
10 Most DANGEROUS Natural Disasters!
How Can Rain Create Conflict? Precipitation and Water Use: Crash Course Geography #11
5.0 / 5 (0 votes)