3. Geological Hazards
A geological hazard is a condition
or event that may cause harm to
property and life as a result of a
geological process such as
earthquake, volcanic eruption, or
landslide.
4. Earthquake
An earthquake is the sudden shaking of the ground caused by the release of energy
from accumulated stress along the geologic faults or by volcanic activity. It may cause
collapse of buildings, tsunamis, landslides, and ground-level changes
An earthquake is ground shaking caused by the sudden and rapid movement of one
block of rock slipping past another along fractures in Earth’s crust called faults. The
energy generated by an earthquake radiates outward in the form of seismic waves from
the source of the quake, called the epicenter, or focus
The three basic types of seismic waves generated by an earthquake are
P waves, S waves, and surface waves. P and S waves travel through Earth’s interior, and
surface waves are transmitted along the surface. Of the three wave types, P waves have the
greatest velocity and, therefore, reach the seismograph station first. Surface waves arrive at
the seismograph station last.
5. Seismographs are
instruments that
detect and record
seismic waves.
The recordings
made by
seismographs are
called
seismograms.
Seismograms are
used to determine
the time and
location of
earthquakes.
6.
7. Earthquake Hazards
Ground shaking
Ground displacement
Liquefaction
Tsunami
Fire
Earthquake hazards are events associated with an
earthquake that may cause adverse effects on
organisms and their environment.
8. Earthquake Hazards
Ground shaking refers to the vibration of the land surface during an
earthquake. The intensity of the vibration depends on the magnitude of the
earthquake and the distance from the epicenter. Ground shaking may cause
partial or total collapse of buildings and structures.
9. Earthquake Hazards
Ground
displacement or surface
rupture is the horizontal or
vertical displacement of the
ground surface along the fault
zone. It affects smaller area
compared to ground shaking.
However, it severely
damages buildings and
structures located adjacent to
the faults.
10. Earthquake Hazards
Liquefaction is the
transformation of solid
rocks and soil to a
liquid‐like state during
ground shaking.
When it occurs, large
rigid structures may
tilt or sink into the
liquefied deposits.
11. Earthquake Hazards
Tsunami is a set
of long, high
ocean waves
caused by an
earthquake or
other disturbance
under the sea. It
causes flooding
and destruction
of structures
near the
shorelines.
12. Earthquake Hazards
Fire is caused by
rupture of gas lines
during ground
shaking and
displacement. It
poses threat of
explosions which
may cause death
and destruction of
property.
13. Bohol Earthquake
On October 15, 2013, a
devastating earthquake
happened in the
province of Bohol. Its
recorded magnitude
was 7.2. The ground
shaking and
displacement caused
major damage of
several government
buildings, schools, and
houses. At least 93
people had been
reported dead after the
earthquake.
14. Volcanic Eruption
Volcanic eruption happens when materials such as magma, ash, and gas are released from a
volcano due to a buildup of pressure inside. The effects of an eruption can be on a local scale
affecting the areas near the volcano (e.g. lava flow reaches nearby towns) or on a global scale
(e.g. volcanic ash particles on air change global temperature).
15. Volcanic Eruption Hazards
Lahar
Pyroclastic fall
Volcanic gases
Tephra falls
Volcanic eruption
hazards are events
associated with a
volcanic eruption that
may cause adverse
effects on organisms
and their environment.
16. Volcanic Eruption Hazards
Lahar is a mixture of volcanic debris and water that flows at the slopes of
the volcano. It destroys infrastructures, buries towns and crops, and fills
river channels.
17. Volcanic Eruption Hazards
Pyroclastic fall is a mass of hot, dry pyroclastic material (mixture of ash and dust)
and hot gases. It moves rapidly along the ground surface. It buries towns and causes
burns, injury, and damage upon impact.
18. Volcanic Eruption Hazards
Volcanic gases are vapors released during an eruption. Some of these gases, such as
hydrogen sulfide (HS) and sulfur dioxide (SO2), are poisonous. They cause respiratory
damage and death.
19. Volcanic Eruption Hazards
Tephra falls are rock fragments and lava blobs ejected by a volcano. They
damage structures, break power lines, kill vegetation, and cause respiratory
damage.
20. Mount Pinatubo Eruption
Mount Pinatubo erupted on
June 15, 1991. This eruption
deposited about 5 km3 of rock
fragments and volcanic ash on
the volcano’s slopes. When a
heavy rain fell on that day, the
rocks and ashes were washed
down into the surrounding
lowlands in large, fast-moving
mudflows called lahar. Lahar
caused more destruction in the
lowlands than the eruption
itself.
21. Landslide
A landslide, also
called landslip, occurs
when earth materials
(rocks, debris, and soil)
move downwards along a
slope. It may be caused
by earthquakes or heavy
rainfall. It can also be
aggravated by human
activities such as
deforestation, blasting,
and construction
23. Landslide Hazards
Mud flow is the flow
of mud and rock. It
may pick up trees,
houses, and cars as
it moves down the
slope. It may block
bridges and
tributaries causing
flood along its path.
24. Landslide Hazards
Earthflow is the
downward flow of
fine-grained
materials, such as
clay, fine sand, and
silt. It is slower than
mudflow, but it
inflicts the same
damage.
25. Landslide Hazards
Rock fall is the
sliding, toppling, or
falling of rocks along
a slope. It disrupts
road traffic in
mountainous
regions. When it hits
a structure or
vehicle, it causes
damage depending
on the size of the
rock and the force of
impact.
26. Southern Leyte Landslide 2006
A massive landslide happened on February 17, 2006 in Southern Leyte. The
landslide caused widespread damage and loss of life. It was followed by
heavy rainfall and a minor earthquake. The official death toll was 1,126.
28. Geological Hazard Maps
A geological hazard map is a map indicating the
areas that are vulnerable to hazards caused by
earthquakes, volcanic eruptions, and landslides.
It is a tool used by scientists and local government
authorities to anticipate any hazard that a
geological event may bring.
It also helps the public be informed and prepared
for the geological hazard.
29. Earthquake Hazard Map
Based on the legend, the
different locations are colored
depending on the number of
earthquake hits for the past 30
years. For example, Baguio
City (Benguet), which is found
in the northern part of Luzon,
experienced 76-100
earthquakes.
30. The top ten provinces that are most
prone to earthquakes are:
1. Surigao Del Sur
2. La Union
3. Benguet
4. Pangasinan
5. Pampanga
6. Tarlac
7. Ifugao
8. Davao Oriental
9. Nueva Vizcaya
10. Nueva Ecija
31. Earthquake Hazard Map
Surigao del Sur, along with Davao Oriental, are
earthquake-prone because they are located
along the Philippine Trench and because of
nearby active fault lines. Deep-focus
earthquakes that are experienced in La Union
and Pangasinan are due to the Manila Trench,
while shallow earthquakes in these areas
together with Nueva Vizcaya, Nueva Ecija, and
Benguet are generally due to their location
along the Philippine Fault Zone. Although
Ifugao experienced fewer earthquakes in the
past, it is still very vulnerable to future
earthquakes.
32. Tsunami Hazard Map
Cyan, magenta, and yellow lines
indicate the potential of the
tsunami and the tsunami
generators. When the earthquake
occurs in the Philippines, then
tsunami is locally generated. On
the other hand, an earthquake
that occurs outside the country
may be a foreign tsunami
generator for the Philippines
33. Map of Distribution of
Volcanoes
Below is the map showing the distribution of
volcanoes all over the Philippines. These
volcanoes are classified as active (red),
potentially active (orange), and inactive
(gray). Places where active and potentially
active volcanoes are prone to hazards of
volcanic activities or volcanic eruptions. For
example, Mayon Volcano situated in Albay in
the Bicol Region, is known not only for its
perfect cone, but also for its volcanic
activities. It has 49 recorded eruptions as of
2013. The areas surrounding the volcano
are highly affected by volcanic hazards. On
the contrary, Palawan is not vulnerable to
volcanic eruption hazards since there are
very few volcanoes near the area and all of
them are inactive.
35. What should you do before, during, and after geological hazards
brought by earthquakes?
Before an
Earthquake
Develop a disaster plan. Determine the
“safe places” in your house. A safe
place could be under a sturdy table or
against an interior wall away from
windows or tall furniture.
Practice "drop, cover, and hold on" in
the safe place. Drop under a sturdy
desk or table, take cover, and hold on.
Take training on first aid from your local
Red Cross chapter. Also, learn how to
use a fire extinguisher.
Discuss earthquake with your family
and/or housemates. Everyone should
know what to do in case the disaster
strikes.
Prepare an emergency supply kit. It
must include non-perishable food,
water, first aid kit, clothes, a battery-
operated radio, flashlights, and extra
batteries.
During an
Earthquake
• Wherever you are, take cover
immediately.
• If you are indoors, drop on the
ground, take cover under a sturdy
thing like a table, and hold on until
the earthquake stops. Stay away
from windows, tall furniture, and light
fixtures. Shattered glass and heavy
objects may hurt you.
• If you are outdoors, go to an open
area away from buildings, trees,
streetlights, and power lines.
• If you are in a vehicle, pull over to a
safe place, avoiding anything that
can collapse. Stay inside the vehicle
with your seat belt fastened until the
shaking stops.
After an
Earthquake
• Check yourself for injuries.
• Help injured or trapped persons if you can.
• Be prepared for aftershocks. Aftershocks are smaller
earthquakes that follow the main earthquake and can
cause further damage to weakened buildings.
• Clean up spilled medicines, bleaches, and gasoline
immediately.
• Open cabinet doors cautiously. Contents may have
been shifted during the shaking.
• Listen to the radio or television for more information
from authorities.
• Stay out of damaged buildings.
• If you are in a coastal area, move to a higher ground.
The earthquake may trigger tsunamis.
• If you are in a mountainous area or near unstable
slopes, be aware of landslide. Soil and rocks may be
loosened by the earthquake.
36. What should you do before, during, and after geological hazards
brought by volcanic eruptions?
Before a Volcanic
Eruption
• Prepare an emergency supply kit. It
must include non-perishable food,
water, first aid kit, clothes, a battery-
operated radio, flashlights, and extra
batteries. Also, include masks and a
pair of goggles for each member of the
family.
• Make an emergency plan. Each
member of the family must know what
to do and how to contact one another
when the disaster strikes.
• Learn about your community's risk from
hazards of volcanic eruptions.
• For government institutions, set-up an
exclusion zone around a volcano for
safety and crowd control. An exclusion
zone is a location where specific
activities are prohibited.
During a Volcanic
Eruption
• Follow the evacuation orders issued
by government officials and
evacuate immediately to avoid flying
debris, hot gases, volcano blast, and
lava flow.
• Be aware of mudflows and lahar.
The danger of these hazards
increases near tributaries. They can
flow faster than you can walk or run.
Look upstream when crossing a
bridge and do not cross it when a
mudflow is approaching.
• Use a dust mask or hold a damp
cloth over your nose and mouth to
prevent inhaling volcanic gases.
Also, cover your skin to protect
yourself from ashfall.
• If you are unable to evacuate,
remain indoors with doors, windows,
and ventilation closed until the ash
settles.
• Listen to the radio for the latest
emergency information.
After a Volcanic
Eruption
• Stay in the evacuation center until the authorities
say that it is safe to go back home.
• Help in cleaning and checking the damages brought
by volcanic eruption hazards.
• When cleaning ashes or mudflows at home, use a
dust mask to cover your nose and mouth. Seek
advice from the authorities regarding the disposal of
volcanic ash in your community.
•
37. What should you do before, during, and after geological hazards
brought by landslides?
Before a Landslide
• Have your parents ask for a ground
assessment of your property.
• Know the patterns of storm-water
drainage near your home. Note
where runoff water converges, and
avoid these places during a storm.
• Learn about the emergency
response and evacuation plans for
your area during a landslide.
• When you suspect imminent
landslide danger, contact the
emergency response team of your
community immediately. Evacuate
immediately and inform neighbors
who might be at risk.
• Consider relocation if living in an
area vulnerable to landslides.
During a Landslide
• Stay alert and awake. Many
landslide fatalities occur when
people are sleeping.
• Stay away from the path of any
landslide hazards. If you
suspect imminent danger,
evacuate immediately.
• If caught in a rock fall and
escape is not possible, roll into
a ball to protect your head.
After a Landslide
• Stay away from the landslide area.
• Listen to local radio for the latest emergency
information.
• Check for injured or trapped persons near the
landslide, without entering the area. Direct the
rescuers to their locations.
• Replant the damaged ground as soon as possible
to avoid landslides in the future.
38. What are other practical ways to cope with geological hazards
caused by earthquakes, volcanic eruption, and landslides?
39. Key Points
Many geological hazards cannot be prevented. However, through careful
planning and preparation, damage to property and loss of life can be
avoided.
Everyone in the family must know what to do before, during, and after
geological hazards brought by earthquakes, volcanic eruptions, and
landslides.
40. Human Activities that Trigger Landslides
Clearcutting
Slash-and-burn
Mining and quarrying operations
Construction activities
Landslides may be triggered by natural processes such as heavy rainfall and earthquakes.
They can also be triggered and aggravated by human activities such as the following:
41. Human Activities that Trigger Landslides
Clearcutting is a method done
by logging companies to cut
down every marketable tree
from a selected area to harvest
timber. Deforestation or
removal of trees that hold
water and topsoil may cause
landslides.
42. Human Activities that Trigger Landslides
Slash-and-
burn or kaingin system
is a method that cuts
down and burns off the
existing vegetation. It is
a form of deforestation
because the land is
converted to other uses.
43. Human Activities that Trigger Landslides
Mining and
quarrying
operations use
explosives in their
blasting techniques to
break rocks and
gather ore deposits.
They cause land
areas to slide due to
the vibrations from
the blast.
44. Human Activities that Trigger Landslides
Construction
activities such as building of
roads and railways may
interfere or change the
natural drainage of water.
When there is heavy rainfall
or flood, water may then
move to a different path
which may saturate slopes
and cause landslides.
45. Ways to Lessen the Occurrence of Landslides
Instead of clearcutting, selective cutting can be adopted by logging companies to allow old
trees to remain. This method cuts down mature or inferior kind of trees to encourage the
growth of the remaining trees in the forest.
Do alley-cropping instead of slash-and-burn method. Alley-cropping is a method of
simultaneously growing an agricultural crop with a tree crop, retaining soil fertility.
Plant more trees with strong root structures that hold the soil together.
The government must set mining rules based on the evaluation of slope stability and
landslide threat in the mining areas. Mining companies must follow these rules. In case of
disobedience, temporary or permanent suspension of mining operations must be
implemented.
Avoid construction on steep slopes. As this is not entirely possible, evaluation of the area for
land development should be performed by engineers and geologists.
Construct proper drainage away from the slope to control water accumulation and to avoid
slope instability.
During construction, do not add an unnecessary weight of fill materials to avoid overloading.
Also, check broken or leaking pipes because oversaturation of soil with water can trigger
landslides.
47. A hydrometeorological hazard is a
condition or an event that may cause
harm to property and life as a result of a
hydrometeorological process such as
tropical cyclone, monsoon, flood, and
tornado or ipo-ipo.
48. Tropical Cyclone
A tropical cyclone is a rapidly
rotating low-pressure system
that forms over tropical oceans.
It is called typhoon in the
Philippines. The typhoons
entering the Philippine Area of
Responsibility (PAR) are given
a local name by the Philippine
Atmospheric, Geophysical,
and Astronomical Services
Administration (PAGASA).
This agency monitors and
disseminates information about
weather disturbances.
50. Tropical Cyclone Hazards
A flood is an overflow of water
over a normally dry land. Due to
heavy rainfall brought by a
typhoon, the water levels in dams
and rivers increase. The water
then overflows to nearby land
areas. A flood can damage
houses, buildings, and bridges.
Flash flood, which is a sudden,
rapid flooding, may cause
drowning and fatal injuries.
51. Tropical Cyclone Hazards
A strong sustained
wind is often brought
by a typhoon. It can
damage or destroy
vehicles, buildings,
bridges, fields, and
plantations.
52. Tropical Cyclone Hazards
A landslide is
the movement
of a mass of
rocks, soil, and
debris down a
slope. It can be
triggered by
heavy rainfall.
53. Tropical Cyclone Hazards
A storm surge is an
abnormal rise of sea
water due to a
typhoon. It is created
when water is being
pushed toward the
shore by the force of
the winds moving in a
circular manner. It
ravages beaches and
coastal areas.
54. Super Typhoon Yolanda
Super Typhoon Yolanda (International name Haiyan) was one of the most powerful typhoons ever
recorded. It caused massive destruction in the Philippines on November 9, 2013. Strong winds,
heavy rainfall, and storm surges caused widespread damage to properties and loss of lives.
About 6000 people died and 28 000 were injured because of the typhoon.
55. Monsoon
A monsoon is a seasonal prevailing wind in the South and
Southeast Asia. It brings a different kind of weather depending on
where it comes from. When it blows from the southwest between
May and September, it brings rainy weather. When it blows from
the northeast between October and April, it brings dry weather. In
the Philippines, the southwest monsoon brings about heavy
rainfall.
56. Southwest Monsoon Hazards
Heavy rainfall and strong wind can damage residential
and industrial buildings. It can also destroy agricultural
crops.
A landslide may happen when the soil becomes
saturated with water due to heavy rainfall. The soil and
rocks from the slope can move down and destroy many
properties along the way.
A flood may occur due to heavy rainfall that saturates
the soil and causes an overflow of water to dry land
areas.
A monsoon may bring about the same hazards caused by a typhoon. It may cause
heavy rainfall, strong wind, landslide, and flood.
57. Marikina River
On August 1 to 8, 2012, the
southwest monsoon
(Habagat) caused typhoon-
like damage in Metro Manila
and nearby provinces.
Heavy rainfall caused the
Marikina River to overflow,
triggered a landslide, and
caused the collapse of roads
and bridges. The floods and
rain left 95 people dead and
damaged 8000 houses.
58. Tornado
An ipo-ipo (tornado)
is a violently spinning
wind on land that
appears like a
funnel-shaped cloud.
It can destroy large
buildings, uproot
trees, and hurl
vehicles
61. Risk to Typhoons Map
• A tropical cyclone (also called bagyo in the
Philippines) is the generic term for any intense
circulating weather system over tropical oceans.
When it originates from the Pacific Ocean, it is called
a typhoon. It may bring about hazards such as heavy
rainfall, strong wind, flood, and landslide.
• The Philippines is located on the western rim of the
Pacific Ocean, an active area for typhoon formation
because of the vast expanse of deep, warm ocean
water. Because of its location, the country
experiences an average of 20 typhoons per year,
about nine of them make landfall. Aside from its
location, it is also comprised of more than 7000
islands, so there are plenty of coasts and shorelines
that could be directly hit by strong winds and heavy
rainfall.
• Because the Philippines is hit by many typhoons in a
year, it is important to study which areas in the
country are at high risk. Below is the map of the
country along with the colors indicating the level of
risk to typhoons.
62. Risk to Typhoons Map
• The dark blue areas on the map are those that have
high risks of being hit by typhoons. For example, the
smaller islands in the northern part, including
Batanes, have very high risk to typhoons. In fact,
these islands are hit by typhoons almost all year
round. Also, Albay in the Bicol region has very high
risk to typhoons. It is often the first area that is hit by
typhoons that move along a westward path.
• On the other hand, those that are colored green have
medium risks, and those that are yellow and tan have
low risks to typhoons. For instance, Mindoro (located
in Southern Luzon) has medium risk, Bohol (in the
Visayas) has low risk, and Bukidnon (and most of
Mindanao region) has very low risk to typhoons.
63. Flood Susceptibility Map
Flood is the overflow of a large amount of water beyond its normal
confines. It is a hydrometeorological hazard that can be caused by heavy
rainfall brought by a typhoon or the Southwest monsoon. It causes
damage to infrastructure and poses threats to the health of residents living
in the area.
Unlike the typhoon risk map which presents the level of risk of different
provinces to typhoons based on their location to the typhoon route, flood
maps are more area-specific. A flood map represents past scenarios of
flood events in the specific area due to the overflow of a nearby water
resource.
64. DOST-Project NOAH
Project NOAH is the Philippines' main disaster risk reduction and
management program. It was initially launched by the Department of
Science and Technology (DOST). It has released hazard vulnerability
maps to help concerned agencies involved in disaster prevention and
mitigation. Included in their maps are flood susceptibility maps
65. How to use Project NOAH
1. Open the website http://noah.dost.gov.ph/#/.
66. How to use Project NOAH
2. Click on the icon Flood
67. How to use Project NOAH
3. In Find a place… type location ex. Aringay, La Union
68. How to use Project NOAH
Provincial, Municipal and Barangay Boundaries can be shown in the map
70. Here are the practical ways you can do before, during, and after a
tropical cyclone or monsoon:
Before the Tropical
Cyclone or
Monsoon
• Prepare an emergency supply kit. It must
include non-perishable food, water, first aid
kit, clothes, a battery-operated radio,
flashlights and extra batteries, and a
whistle.
• Make sure you have an adequate supply of
non-perishable food and clean water at
home.
• If you live in a place that is in the path of the
cyclone or monsoon, close all doors and
windows.
• Check your drainage system at home. An
efficient drainage system will lessen the
chance of flooding and leaks.
• Check to see if there is a need to fix roofs,
ceilings, doors, and windows.
• Frequently listen to the weather reports.
• Charge up emergency lights, electronic
communication devices such as cellphones,
and power banks. There is a high
probability of power outage due to strong
winds and heavy rainfall.
• Identify a safe area for evacuation.
During the
Tropical Cyclone
or Monsoon
• Closely monitor weather reports for
updated information on the tropical
cyclone (storm signal numbers or
storm surge advisory) or monsoon.
• If you are in an area being directly
hit by the hazard, stay indoors as
much as possible.
• Evacuate when necessary and bring
your emergency supply kit.
• In case of a threat of a storm surge,
evacuate to a place higher than 500
meters from the coast.
During the
Tropical Cyclone
or Monsoon
• If your house was heavily damaged, ask for
the advice of authorities regarding its safety
and stability. Do not go inside the house if
you are uncertain of its condition.
• Check gas, water, and electrical lines for any
damage.
• Beware of animals such as snakes that may
have entered your house.
• Wear protective gears when cleaning up
debris.
• Some roads may be closed due to flood. If
you come upon a barricade or a flooded
road, turn around and use another route.
•
71. Here are the practical ways you can do before, during, and after a
flood:
Before the Flood
• Create a family disaster plan.
Designate a contact person who can be
reached and discuss where you will
meet if family members are separated.
• Closely monitor weather reports for
information on the possibility of
flooding.
• Identify a safe place for evacuation and
alternative routes that are not prone to
flooding.
• If a flash flood warning is issued in your
area, evacuate to a safe place
immediately.
• If flood alert is issued in your area,
move valuables and furniture to higher
levels and disconnect electrical
appliance.
• Prepare and emergency kit and
supplies like food and water.
During the Flood
• If you see any signs of flood, turn off the
main source of electricity and go to a
higher place such as the second floor or
attic.
• Do not wade along flooded areas to keep
yourself from having water-borne
diseases.
• In case you need to pass through the
flood, wear protective gears such as
boots and raincoats.
• Follow any evacuation orders.
• Watch out for live wires or any electrical
outlet submerged in water.
• If you are inside a vehicle and water rises
around it, leave it immediately. Climb to
higher ground as quickly as possible.
• If you see someone falls or is trapped in
flood water, do not go after the victim.
Throw the victim a floatation device such
as tire, large ball, or ice chest. Then ask
help from a trained rescuer.
After the Flood
• Have an electrician inspect your house
wirings and electrical outlets before using
them.
• Clean up your house. Dispose of things that
may be used by mosquitoes to breed like
water vase and anything that can hold
stagnant water.
• Boil water before drinking because it may
have been contaminated.
• Do not go or return to flooded areas until the
authorities say that it is safe to do so.
72. Here are the practical ways you can do before, during, and after an
ipo-ipo:
Before an Ipo-ipo
• Know the safe places where you can hide
when there is an ipo-ipo. The safest
place is underground. If your house does
not have a basement, a small room in the
middle of the house away from the
windows is best.
• Pay attention to weather reports about
the possible occurrence of an ipo-ipo.
Familiarize yourself with the warning
sign. An ipo-ipo is often accompanied by
strong typhoons. Watch out for clouds
that begin to rotate in a circular pattern.
• Create a family disaster plan. Designate
a contact person who can be reached
and discuss where you will meet if family
members are separated.
• Prepare and emergency kit and make
sure that there is an ample supply of food
and water.
During an Ipo-ipo
• If you are inside a house, move to a
safe place. Get under a steady piece
of furniture, such as a heavy table.
Hold onto it and protect your head.
• If you are inside a vehicle, get out and
seek a safe shelter.
• If you are outdoors and there is no
shelter to hide, lie down in a low area
with your hands over your head and
neck. Always watch out for flying
debris.
• If you are inside a high-rise building,
move to a room on the lowest floor
After an Ipo-ipo
• Check yourself for injuries.
• Check for injured or trapped persons. Help if
you can, but do not move them unless they
are in immediate danger of further injury.
• Wear protective gears when walking and
working through the debris.
73. Key Points
It is important to know what to do before, during, and after a
hydrometeorological hazard.
Create a family disaster plan and educate everyone on what to do during
and after the occurrence of the hazard.
Be calm when the hazard strikes and carry out the disaster plan.
Continue practicing safety procedures even after the occurrence of the
hazard.
Emergency numbers of government offices or NGOs which can respond
immediately should be noted and kept handy.
75. Coastal Processess
Coastal processes are naturally-occurring processes that bring
alterations to the coastal zones. They are interactions of marine, physical,
meteorological, geological, and biological events.
76. Waves
Waves are created by the energy of the wind on the sea. The wind causes
water particles to rotate and produce waves. Large waves are usually
formed during storms and typhoons. The height and energy of the waves
vary on wind speed, duration of the wave, fetch, and water depth. Fetch is
an area of a water wave where the wind blows in a constant direction. The
higher speed, longer duration, wide fetch, and deeper wave have more
energy than other types of wave.
77. Types of Waves
Constructive waves have low energy and have a stronger swash (a
wave that approaches the coast) than backwash (a wave that recedes
from the coast). They are responsible for material depositions.
Destructive waves have a higher height and energy. They are significant
forces of change in the coasts. In destructive waves, the backwash is
much stronger than the swash. Because of this, the coast has a higher
tendency of erosion. Strong destructive waves can carry a great load of
sediments that could significantly alter the coastal landscape.
78. Tides
Tides are temporary fluctuations in sea levels due to gravitational forces
between the sun, the moon, and the earth. They carry less energy to the
coasts but occur more often than waves. High tides occur when water
levels are at their highest while low tides occur when water levels are at
their lowest.
Low-lying locations get submerged in seawater during high tide leading to
submersion. Repeated exposure of the coasts to submersion can loosen
materials and cause erosion in the long run.
79. Sea Level Rise
Faster sea level rise has been observed in the recent years. This is due
to the warming of the sea and melting of glaciers. The rise in sea level has
become more permanent. This warming of the sea and melting of glaciers
are due to enhanced greenhouse effect brought about by carbon
emissions from various human activities. Islands and even some countries
are in danger of being submerged underwater if the sea levels continue to
increase. Sea level changes threaten low-lying areas to experience
submersion permanently
80. Crustal Movements
Continents and landmasses have been formed and continuously shaped
by the movement of tectonic plates. These plates move because of the
accumulated stress within the Earth's crust releasing energy and forming
different landmasses. Coastal areas can be changed by the movement of
these plates.
Crustal movements can cause erosion, submersion, and saltwater
intrusion along coasts. Its major effect is erosion followed by submersion
as a subsequent effect. It can also cause low-lying areas and islands
adjacent to oceans or seas to sink. Saltwater may also enter freshwater
basins if crustal movements would cause cracks in the coastlines.
81. Storm Surge
Storm surge occurs when the wind from tropical cyclones cause sea
water levels to be unusually higher than high tide levels. It can go as high
as 20 feet or more above the normal sea level. It is more likely to occur on
coasts with gentle slopes than those with steep slopes.
Some locations experience submersion during storm surge, which is not
experienced during high tides. Erosion is also more likely to happen
because of the additional actions of waves during storm surge. Inland
groundwater sources experience saltwater intrusion. This happens when
the seawater reaches the coastal areas and gets into groundwater and
other freshwater resources.
82. Key Points
Coastal processes are natural events that affect the features of coasts and
nearby areas.
The three primary effects of coastal processes are erosion, submersion, and
saltwater intrusion.
Tides cause an increase or a decrease in sea levels. Locations with increased
sea level (high tide) are exposed to the dangers of submersion. Constant
submersion can also lead to erosion.
The rise in sea levels causes submersion of low-lying areas.
Crustal movements cause erosion, submersion, and saltwater intrusion.
Storm surge endangers areas near coasts to submersion. Erosion can also
occur because of wave action on storm surges. Saltwater intrusion can also
happen if the seawater reaches wells and reservoirs of freshwater.
84. Coastal Protections
Seawalls and bulkheads are structures that are built parallel to shores
that protect the coasts from wave actions.
Groynes and jetties are structures that are built perpendicular to shores to
prevent coastal erosion by promoting beach build-up as they trap sand.
Breakwaters are offshore structures that protect coasts from parallel
waves and in turn, prevent erosion and submersion.
Beach nourishment is a method where a large amount of sand is added
to the coasts. This will create a new beach or widen an existing one.
However, this method is costly which deters communities to use it.
Sandbags are used to counteract waves that hit the shores. They also
diminish the effect of a storm surge that can cause submersion.
Some structures and methods can help protect the coasts from erosion and submersion. They
are usually constructed along the coasts.
85. Reducing Coastal Erosion
Development of infrastructures must be constructed in safe distances
from the coasts.
Beach dewatering involves pumping out water from the shores to prevent
erosion.
Artificial seaweeds can be placed in the water near the coasts to reduce
the speed of current that promote erosion.
Ban of mining activities near coasts prevents erosion caused by mining.
Plant cover and vegetation around coasts aid in protecting coasts from
erosion.
Aside from coastal protection, different ways can be done to reduce the impact of coastal
erosion. Some of them are less expensive than constructing structures along the coasts.
86. Coping with Saltwater Intrusion
Monitoring and assessment ensure effective management of saltwater
intrusion cases.
Regulations from governing units aid in coping with saltwater intrusion.
Structures must be regulated to have a safe distance from the sea to
prevent excessive groundwater extraction from the reservoir that
contributes to saltwater intrusion.
Artificial recharges pump freshwater to the reservoir to prevent saltwater
from intruding through the coasts.
Barriers can be constructed along coasts to prevent further advancement
of saltwater if already present.
The following methods help in dealing with saltwater intrusion.
87. Mitigation of the Impacts of Land
Development, Waste Disposal, and
Construction on Coasts
88. Mitigation of the Impacts of Land Development, Waste
Disposal, and Construction on Coasts
Human activities such as land development, waste disposal, and
construction cause different changes in coastal features. It is vital that
impacts of these activities be prevented or mitigated to help the coasts in
withstanding coastal processes.
89. Coastal Land Development
Coastal land development is due to the demand in space, structures, and facilities
that are used for various human needs. It aggravates the effects of coastal processes. It
increases the incidents of sand mining and sediment run-off that contribute to coastal
erosion. In addition, the increase in establishments leads to higher demand for
freshwater which then contribute to saltwater intrusion.
Several ways must be employed to control the impact of land development on coasts.
In the Philippines, PD 1586 has established the implementation of Philippine
Environmental Impact Assessment (EIA). EIA allows the determination of the
possible environmental consequences of implementing a project, and it also plans
possible preventive and enhancing methods for mitigation of the determined risks. EIA
points out the dangers before, during, and after development.
Meanwhile, environmental risk assessments (ERAs) are done in an ongoing project
and help identify and evaluate the effects on the ecosystem of any hazards caused by
land development. Developments must also have blueprints that ensure that coasts are
preserved, infrastructures are used efficiently, and the development itself has a
beneficial use for the community. Lastly, controlling activities of development must be
employed to ensure the protection of coasts from strain.
90. Waste Disposal
The increase in development and population may lead to increased
amounts of waste disposed of in a coastal area. The wastes are
sometimes disposed of in landfills built near the coasts. The construction of
these landfills not only causes land and water pollution to the coastal area
but also amplifies the effects of coastal erosion and results in saltwater
intrusion.
Effective solid waste management planning and implementation must
be carried out by the residents and users of coastal areas. Managing solid
wastes at the community level prevents coastal deterioration. Industrial
wastes must also be properly managed and not released in coastal areas.
91. Construction
Constructions on coasts are consequences of the increasing land
development in the area. If done haphazardly, these constructed
infrastructures can cause more harm to the coast.
It is crucial that these structures are built at a safe distance from the
coasts. This ensures both the structures’ and coasts’ safety. Structures
must also have strong foundations to withstand the coastal harshness so
that they will not deteriorate. It is also suggested that the buildings be
elevated so as not to impact directly the coastal soil and for their protection
against coastal processes. If possible, reinforcing building
envelopes should be considered to protect the infrastructure and land
from coastal threats. Building envelopes are structures that separate
interior from exterior, like walls, doors, roofs.
