Landslides occur when slopes of earth or rock fail and move downslope due to gravity. They are caused by both internal factors like steep slopes and groundwater, as well as external triggers from earthquakes, heavy rain, or construction blasting. Common types include debris slides of unconsolidated material, rock slides, and mudflows. Engineering measures can help prevent landslides, such as benching slopes, installing retaining walls, laying riprap, building gabion walls, applying shotcrete, installing drainage systems, and planting vetiver grass to stabilize soil. Proper landslide preparedness also involves hazard mapping and restricting settlements in high-risk areas.

1. Landslide
This Photo by Unknown Author is licensed under CC BY

2. Landslides
(rainfall induced)
• A massive outward and
downward movement
of slope forming due to
gravity.
• Mudflow, debris flow,
earth failure and slope
failure
This Photo by Unknown Author is licensed under CC BY-SA

4. Landslide or
mudslide (mudflow)
• Occur when heavy
rains or rapid snow or
ice melt or an
overflowing crater
lakes loosens
• Crush, burry people
and buildings
This Photo by Unknown Author is licensed under CC BY-SA

5. Landslides
• If a mass of earth moves
along a definite plane or
surface the failure is
termed as Landslide
• Large block known as a
slump block moves during
the landslide.
• The scar above a landslide
is easily visible.

6. • Debris slides - are failure of
unconsolidated material on a
surface;
• Rock slide or Rock Fall – where
movement of large rock block rolls
• Pore Water Pressure is the key to
monitoring landslides.
• Shear strength decreases

7. CAUSES OF LANDSLIDES
• LANDSLIDES OCCUR DUE OF VARIOUS REASONS
• Internal Causes:
• Influence of slope- Provides favorable condition for
landslides; steeper slope are prone to slippage of land.
• Ground water or associated water- Main factor
responsible for slippage. Suppose the hard or massive
rocks are underlined by softer rocks (shale or clay bed)

8. • External factors
• Most common is the vibration resulted
due to earthquakes; blasting to
explosives; volcanic eruption etc.
• Earthquakes often initiate mass failures
on large scale

9. Landslide preparedness
• Hazard mapping

11. Public
information
• restricts settlements
in landslide prone
area

12. Engineering intervention measures or slope
protection measures
Benching, Brgy. Puguis, La Trinidad, Benguet
Slope stabilization
art of cutting side slopes in steps
is the process to solidify and stabilize the slopes on
the way.

16. Retaining walls
• Retaining wall, Brgy.
Eastern Poblacion, Poro,
Cebu
• retaining walls are
relatively rigid walls used
for supporting soil laterally
so that it can be retained at
different levels on the two
sides

18. Riprap, Balut Island,
Sarangani, Davao Occidental
Riprap-permanent layer of
large, angular stone, cobbles, or
boulders typically used to armor,
stabilize, and protect the soil surface
against erosion and scour in areas of
concentrated flow or wave energy.

21. Gabion walls
• soil stabilization behind the wall
• gabion baskets that are stacked in
one
or more rows. (cage)

23. Shotcrete
-permanent and cost-effective solution for
retaining wall construction.
-special mix of high-strength concrete

25. Drainage
- is a tunnel or channel created to
drain water, often from a stagnant or
variable-depth body of water.

26. Vetiver grass
-helps to stabilise
soil and protects
it against erosion,
but it can also
protect fields
against pests and
weeds.