SUBMITTED TO:-

PROF. ARCHEE VERMA

SUBMITTED BY:-

ANAND SWAROOP JAICHANDRAN

4TH YEAR SEM-VIII

M.I.T.S. GWALIOR (M.P.)

Landslides are defined as mass movement of rock, debris or earth down a slope and

have come to include broad range of motions whereby falling, sliding and flowing

under the influence of gravity dislodges earth material.

Take place in conjunction with

I. Earthquakes

II. Floods/ prolonged rainfall

III. Volcanoes

Hilly terrain is highly sensitive to landslides – Himalayas and Western Ghats

Landslides can do great damage and change the land very quickly.

If a slippery material is present below soil then soil can become heavy with rainwater

and prone to landslide. It is a downward or outward movement of soil, rock,

vegetation due to gradient. This movement can be fall, flow, slide, spread or topple.

Landslides occur usually at steep slopes but these may occur in areas with low slope

gradient.

LATERAL SPREAD- Spread is defined as an extension

of a cohesive soil or rock mass combined with a

general subsidence of the fractured mass of cohesive

material into softer underlying material.

ROTATIONAL SLIDES- It move along a surface of

rupture that is curved and concave.

TRANSITIONAL SPREAD- In translational slides the

mass displaces along a planar or undulating surface of

rupture, sliding out over the original ground surface.

CREEP- It is spatially continuous movement in which

surfaces of shear are short-lived, closely spaced, and

usually not preserved its speed is extremely slow.

ROCK FLOW- Extremely rapid, massive, flow like

motion of fragmented rock from a large rock.

In the following table shows a schematic landslide classification adopting the classification of Varnes

1978 and taking into account the modifications made by Cruden and Varnes, in 1996. Some integration

has been made by using the definitions of Hutchinson (1988) and Hungr et al. 2001

A. Natural Factors

Gravity – works more effectively on steeper slopes

Geological factors – weak, sensitive or weathered materials

Heavy and prolonged rainfall – rapid rise in water level and saturation

Earthquakes – plate tectonic moves the soil that covers it also moves

Forest fire – causes erosion and induce floods and landslides

Volcanoes – kill vegetation over extensive area and spreads volcanic rocks,

subsequent

rainy season will trigger landslides

Waves – can erode the beach or the toe of a bluff, cutting into slope Freezing

and Thawing

Landslides occurs when several factors converge:-

B. ANTHROPOGENIC FACTORS

Inappropriate drainage system – natural drainage lines on slopes areblocked by terracing/ contour bounding

Cutting and deep excavations on slopes for buildings, roads, canals andmining – modification of natural slopes, blocking of surface drainage,loading of critical slopes and withdrawal to toe support

Change in slope/ land use pattern, deforestation, settlements, agriculturalpractices on steep slope.

C. HUMAN ACTIVITIES

Deforestation, Cultivation and Construction when destabilize the alreadyfragile slopes.

Vibrations from machinery or traffic, blasting, Construction.

In shallow soils, the removal of deep-rooted vegetation that bindscolluviums to bedrock.

Landslides occurs when several factors converge:-

Landslides destroys everything and anything that comes in their path.

•Roads

•Rail lines

•Lines of communication

•Settlements

•River flows/ Damming

•Agricultural production

•Land area

•Flooding

•Water availability, quality and quantity

•Flora and Fauna

Fatalities depends on the place and time of occurrence.

Estimated casualties per year, world-wide: 600 - 1000 persons.

HOTSPOTS

• Anywhere with steep slopes and weathering

•High mountain ranges, sheer cliffs, and steep sided river valleys

•Where volcanoes erupt and along coasts

EXAMPLE

S

•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, and ancillary structures such as decks and

patios tilting and/or moving relative to the house.

•Sticking doors and windows, and visible open spaces.

•Broken water lines and other underground utilities.

•Leaning telephone poles, trees, retaining walls or fences.

•Sunken or dropped-down road beds.

•Rapid increase in a stream or creek water levels, possibly accompanied by

increased turbidity (soil content).

•Sudden decrease in creek water levels even though rain is still falling or just

recently stopped.

Prevent landslides and neighborhood drainage problems in

landslide prone areas:-

•Water is the most common cause of unstable slopes, landslides, and erosion. Check your

home's drainage system. Maintaining the drainage system on private property is the

owner's responsibility. Make sure your drainage system directs water away from your

foundation and not on to your neighbor's property.

•Never discharge water over the side of a steep hill.

•Clean your gutters and downspouts. Check your gutters once a week during fall and

winter. Just one wind or rainstorm can clog a well-flowing drainage system.

•Clean your gutters and downspouts. Check your gutters once a week during fall and

winter. Just one wind or rainstorm can clog a well-flowing drainage system.

•In general, trees and plants with strong root structures help prevent soil erosion but do

not prevent landslides

•Never block any part of the city's drainage system. Do not put leaves, dirt, grass

clippings, or any materials in ditches, culverts, or drains. Doing so can cause flooding. It

is against the law to dump any material into the drainage system.

MEASURES TO REDUCE THE CHANCE OF LANDSLIDES:

•Vegetation cover protects land from landslides and soil erosion. Therefore efforts should be

made to maintain greenery particularly on slopes. Provisions should be made at community

level to prevent people from excavating, removing materials from the soil or cutting trees.

•Trees should be planted on slopes and slopes base to prevent erosion. Record of erosion,

landslide masses and falling rocks should be maintained.

•During construction a building on a slope design that suits the natural slope should be

adopted.

•Vegetation and trees should not be removed while constructing. Natural streams or drainage

paths should not be constructed during construction. Surface water should be diverted

towards the natural galley enabling water to quickly drain away from the slope.

•Quickly move out of path of the landslide or debris flow.

•If inside a building, stay inside and take cover under a desk, table or other sturdy

furniture.

•If escape is not possible, curl into tight ball and protect your head.

PRECAUTIONS DURING LANDSLIDE:

PRECAUTIONS DURING LANDSLIDE:

•Check for injured and trapped persons, without entering the slide and direct and

assist rescuers.

•Help vulnerable group persons in neighbourhood for emergency assistance.

•Listen to local radio or television station.

•Watch for flooding, which may occur after a landslide or debris flow.

•Look for and report damaged utility lines to authorities.

•Replant damaged ground as soon as possible since erosion caused can lead to flash

flooding.

•Seek professional advice for evaluation of landslide hazard and designing corrective

techniques to reduce landslide risk.

LANDSLIDE IN HILLY AREADEMOLISHED ROAD

LANDSLIDE BLOCKING THE HIGHWAY DEMOLISHED HOUSES BY LANDSLIDE

•Western Ghats

– A: Kerala: small catchment

– B: Nilgiri: transportation corridor

• Himalayas:

– C: Okhimath: high Himalaya, large area

– D: Darjeeling: middle Himalaya, watershed .

•Aruvikkal catchment : 9.5 km2

•Sub catchment of Tikovil River

•History of debris flows during the

monsoons

•Dominant rock type: Charnokites

•UNU‐ITC – CESS debris flow

research catchment

•Rubber plantation area

•Clear relation landuse ‐landslides

• Kurseong in the Darjeeling

district

• Elevations in the study area

vary from 236 m to 2189 m

• Annual precipitation in the

area varies from 2000 to 5000

mm

• metamorphic rocks of the

Himalayan Fold‐Thrust Belt

(FTB)

• foreland molasse basin in the

south

• Main Boundary Fault (MBT)

• Main Central Thrust

• Most landslides are structurally

controlled

(a) A deep‐seated rock wedge

(W_Fol x J2) within Daling

metasediments,

(b) Plane failure (P_Fol) along

foliation surface (Fol) in

sheared phyllonitic rocks

(c) Toppling (T_J1) caused by

steep‐dipping SW‐dipping

joint plane (J1) within

quartzo‐feldspathic gneiss

Retrogression of a deep‐seated

rock wedge slide.

EXAMPLES

CASUALTIES

“A kind gesture can reach a wound that only compassion can heal.”