Chapter 6 discusses rainfall-induced landslides, their causes, and indicators of impending geological hazards, such as tension cracks and observable movements in trees. It highlights sinkholes, including both natural and human-induced causes, particularly in areas with soluble rock like limestone. Additionally, it emphasizes the importance of assessing disaster risks and understanding the impacts of events like super typhoon Yolanda on affected regions.

1. CHAPTER 6
Other Related
Geological

3. Rainfall-Induced
Landslide
A landslide is a
massive outward and
downward movement
of slope-forming
materials.
Landslide as a

4. Rainfall-Induced
Landslide
 Causes of Landslide
Groundwater pressure acting to
destabilize the slope
Erosion of the toe of a slope by rivers or
ocean waves
Weakening of a slope through saturation

5. Sinkhole
sSinkholes are common where the
rock below the land surface is
limestone, carbonated rock, salt
beds, or rocks that can naturally be
dissolved by groundwater circulating
through them.
Sinkholes are dramatic because the
land usually stays intact for a while

6. Sinkholes can be human-induced
1. New sinkholes have been
to land-use practices, especially
from groundwater pumping and
from construction and development
practices.
2. Sinkholes can also form when
Sinkhole
s

7. Signs of
Impending
Geological
Hazards

8. Landslide
Earlier Landslide as an indicator
Observing old landslides is a good
indication that the area has unstable
geology, and that more landslides are likely to
happen in the future
Tension Cracks
Tension cracks are created by the stress of

9. Landslide
Things Moving
Observable movement and deformation of
things are also indicators of an impending
landslide. The most common among these is
that trees are bending up in a J-curve as a
sign that the ground slips out from under
them
Water Doing Something Different

10. Sinkholes
Trees or fence posts that
tilt or fall
New small ponds that
appear after rain
Sudden drainage of a pond

11. Assessment:
1. Explain the meaning of disaster.
2. Differentiate the risk factors underlying
disaster
3. Describe the effects of disaster on human’s life
4. Explain how and when an event becomes a
disaster

12. OUTPUT:
A. Based on your understanding, identify some
areas in the Philippines that are exposed to
hazard. Using a table, indicate what potential
hazards these areas/locations are exposed to.
B. Read an account of Super Typhoon Yolanda
that struck Samar and Leyte in 2013. Analyse
its impacts from the different perspectives:
Physical, Psychological, Socio-cultural,

13. END of
chapter 6