Recognition. Prevention, Control, and Mitigation to Landslides

1. Assume that you will build your own house…
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2. Would you build it yourself? Or with the help of others?
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3. What we usually know is that we just build.
As a homeowner, WE should follow this
guide for safety of US and the HOUSE
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5. Most important thing to do when a situation
might occurred
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6. If you are in immediate danger
•EVACUATE IMMEDIATELY
Note that look for safe place and avoid any
possible danger in your way out.
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7. •INFORM YOUR NEIGHBORS
Do not be selfish. Life is important28/08/2019 Barlam, Jolina M. 7

8. •CALL FOR POLICE AND FIRE DEPARTMENT
Stay calm during the call and ask for immediate help
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9. Tell briefly what exactly happen and ask what should do and where are
the places safe to go,
•CALL A REGISTERED GEOLOGIST OR A
GEOTECHNICAL ENGINEER.
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10. WARNING SIGNS
‫ﻩ‬House making noises ‫ﻩ‬ Walls and floors are tilting ‫ﻩ‬Cracks in the house are
actively opening
‫ﻩ‬Cracks in ground are appearing ‫ﻩ‬Water in drainages becomes irregular or
stops
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12. I. DEFINITION
• LANDSLIDES occurs when masses rock. soil, or debris move
down a slope under the force of gravity.
• The term landslide includes a wide rage or ground
movement such as rock falls, mud and debris flows, and
surface called slums, earthflows, and traditional slides.
• Landslides can occur in a matter of
seconds or over the course of weeks
longer.
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13. II. TYPES OF LANDSLIDES
1. SLIDES (Translational or Planar)
Down-slope movement of soil and/or
rock on a plane of weak material can occur on
relatively moderate to steep slopes, especially
in weak geologic materials
2. ROCK FALLS
Rapid, near vertical, movement of rocks
that involves free-falling, bouncing, and rolling;
often occurs on moderate to steep slopes.
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14. 3. SLUMPS (Rotational)
Unconsolidated materials (such as soil and
debris) move down-slope in a distinctive
rotational motion, usually occurs on moderate to
steep slopes.
4. EARTH FLOWS
Unchannelized flow of water, soil, and
vegetation that moves down-slope, occurs on
steep slopes. No failure surface at bottom.
5. DEBRIS/MUD FLOWS
Rapidly moving, channelized slurry slow of
water, soil, rock and vegetation; occurs mainly in
drainage channels.
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15. III. CAUSES OF LANDSLIDES
• Two forces affecting landslides are:
1. Driving Forces (DF) causes to move
2. Resisting Forces (RF) stabilize the slope and prevent movement
• When driving forces exceed the resisting
forces, landslides occur
• To prevent mitigate landslides, increase
resisting forces or decrease driving
forces.
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16. • Factors increasing Driving Forces
1. Over- Steeped slopes
2. Adding water to slope from landscape irrigation, roof downspouts, broken
sewer and water lines, and poor storm water drainage
3. Heavy rainfall and/or rapid snowmelt
4. Loading extra material at the top of the slope .
Earthquakes and heavy precipitation can also trigger lanslides on
susceptible slopes
• Factors increasing Resisting Forces
1. Removing excess water from slopes
2. Adding buttress material at base
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17. IV. LANDSLIDE RECOGNITION BEFORE
YOU BUILD SIGNS OF LANDSLIDE
POTENTIAL OR ACTIVITY
• Steep slopes- problems occur on slopes steeper than 10-15
degrees
Suspect landforms may indicate past ground movement.
Landforms such as steep curved scarps are common at the top
of landslides. Hummocky (lumpy and bumpy) ground often
indicates a former landsides. Trees that lean in different
directions or have bent lower tree trunks (trees with knees)
are also indicators
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18. Upper part of the Oso, Washington landslide site28/08/2019 Barlam, Jolina M. 18

19. ‘Trees with Knees’28/08/2019 Barlam, Jolina M. 19

20. Down-dropped Roads28/08/2019 Barlam, Jolina M. 20

21. •To learn where landslides have occurred in
your area contact local officials, state
geologic surveys, departments of natural
resources, or university geosciences
departments. Slopes where landslides have
occurred in the past have higher likelihood
of movement in the future
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22. Top 10 Most Landslide Prone Provinces of the
Philippines
• Marinduque
• Rizal
• Cebu
• La Union
• Southern Leyte
• Benguet
• Nueva Vizcaya
• Batangas
• Mountain Province
• Romblon
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23. WHEN YOU BUILD
Buildings should be located away from high risk areas such as
steep slopes, rivers and streams (perennial or ephemeral), and
fans at the mouth of mountain channels. Consult a certified or
licensed engineering geologist (CEG or LEG) or a registered/
licensed geologist (RG) or a professional geotechnical engineer
(PE) if you plan on building on a location that is a high risk
area.
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24. School House at Risk
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25. House at Risk
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26. AREAS PRONE TO LANDSLIDE INCLUDE
• Areas where previous landslides have occurred
• Steep natural slopes particularly in weak geologic materials
• Canyons and areas in or around drainages
• Developed hillsides where landscapes are irrigated
• Below cliffs or hills outcrops of fractured rocks
• Steep slopes where surface runoff is directed onto the slope
• Areas where wildfires or human modification have removed
vegetation from the slopes
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