For educational purposes only

1. Rainfall-induced
Geologic Hazards

2. Types of Rainfall-induced Geologic
Hazards
Landslide – a landslide,
also called
“LANDSLIP,” is a
ground movement on a
sloping terrain.

3. Types of Rainfall-induced Geologic
Hazards
Sinkhole – occur in areas
where the soil foundation
is made of soft minerals
and rock such as silicate
materials, salt beds, or
any acidic rocks.

4. Formation of sinkhole

5. Signs of impending Landslides or Sinkhole
1. Springs, water seepage, or
water saturated grounds in
areas that are not typically
wet
2. Soil that
loosens and
moves away
from
foundations
3. New cracks or unusual
bulges on cemented
ground or walls
4. Underground utility lines that
are broken due to vibrations or
tremors from the surface of the
ground
5. Buildings, poles, walls, and fences that are
leaning
6. Sudden rapid flow
of creek waters
carrying more silted
water
7. For sinkholes, there are
signs of an imminent danger in
groundwater that does not
provide the same amount and
quality as before or has
become cloudy, acidic, silted,
or soiled.
9. Ponds that have recently
formed or puddles that grow
or have never disappeared
8. Sign posts or poles that are suddenly
leaning, slumping, sagging, slanting, or
bent

6. Scientific Tools for Assessing
Landslides and Sinkholes
For landslide
In areas that are
susceptible to
landslides, an Abney
level or a laser
rangefinder equipped
with a tiltmeter is
used to measure the
slope angle, soil
compaction, and soil
strength of an area.

7. Scientific Tools for Assessing
Landslides and Sinkholes
For Sinkholes:
Sinkholes are valeted
using ground-
penetrating radar to
provide images of
subsurface ground. It
can detect the type of
objects, changes in
material, and voids
and cracks under a
layer of soil.

8. Precautionary
measures in case of
a landslide or a
sinkhole

9. Landslide
If your area is prone to landslides
Plant more trees, grasses, and other vegetation to prevent
erosion and for compaction of soil.
Build channels for diversion of mudflow or debris flow to
direct the flow away from your property. Make sure
though that the diversion does not affect any neighbor or
any property and/ or cause more significant damage as a
result.
Do not build your house on or near steep slopes, mountain
edges, drainages, or natural erosion valleys.

10. Before a Landslide
Be familiar with your surroundings. Watch for any changes
in appearance or positions of these objects. When there is
a sudden debris flow, this could be a good indicator of an
incoming landslide.
Avoid open storm-water drainage and runoff as these
areas are likely to receive debris and soil from higher
elevations, especially when there is a storm or heavy
rainfall.
Be updated on news regarding the condition of your area.
Be aware of the disaster plans of your local government ~
Learn and participate in emergency response and evacuation
plans for your community.

11. During a Landslide
 Be attentive to unusual sounds such as cracking objects,
moving debris, and rolling boulders
Stay away from the path of debris. This is more
dangerous if mudflow occurs because it increases in
strength as it meets more water from ponds or streams
and it could be aggravated by heavy rain
Stay on elevated and sturdy area. Avoid low lying areas
and steep slopes.
If escape is not possible, curl into a tight ball and protect
your head. Find a structure that can serve to protect you
from the flow of debris

13. After a Landslide
 Avoid the slide area. There is still danger of more
landslides
Listen for the latest emergency information. Follow
warnings and instructions by the local government.
If landslide is caused by rainfall, watch out for
flooding as it will follow the same path taken by the
debris flow
Check for injured or trapped people near the slide, and
for damaged structures and other potential
hazards.Report these immediately to the rescuers or
authorities.

14. Sinkholes
 If sinkholes are not detected earlier and it
appears suddenly, do the following.
Find a refuge in a stable ground of open area.
Wait until the structures on and around the
sinkhole stops moving. Do not attempt to go back
and retrieve your belongings
Wait for the local government's announcement when
it is safe to go back.

15. After a Sinkhole’s Appearance
Stay away from the sinkhole
Monitor the damages on objects. For example, if
the crack gets longer or wider, the sinkhole may
still be enlarging
Do not throw anything into the sinkhole. Anything
thrown into it may contaminate the groundwater
Secure whatever is left of your properties and
relocate to safe grounds, preferably far from this
location because the same bedrock soil or soil
profile may characterize the vicinities of the
sinkhole.

16. Group Activity
What factors would you consider
evaluating the likelihood of a
landslide, and how would you
communicate your findings to the
community in a way that is
understandable and actionable?