Fundamental Concepts Related To Natural Hazards
Natural process have service functions.
Hazards are predictable.
Linkages exist between hazards and physical and biological environment.
Hazards that previously produced disasters are now producing catastrophe
Risks from hazards can be estimated.
Adverse effects can be minimized.
Land movement disasters
Land movement disasters are disasters that occur on land. Some land
movement disasters are earthquakes, avalanches, volcanic eruptions, wildfires,
landslides and many more.
Water Disasters are disasters that occur in water such as oceans, rivers, lakes,
etc.Some types of water disasters are droughts, tsunamis, tidal waves, floods, and
Weather disasters are disasters that occur with the weather and causes changes
in the weather. Some types of weather disasters are tornadoes, cyclones,
hurricanes, blizzards, lighting, thunderstorms.
• The shaking or trembling caused by the sudden
release of energy
• Usually associated with faulting or breaking of rocks
• Continuing adjustment of position results in
Global Earthquake LocationsGlobal Earthquake Locations
A volcano is an opening in theA volcano is an opening in the
planets surface which letsplanets surface which lets
hot, rocks, ash, molten lava,hot, rocks, ash, molten lava,
and gases onto the surfaceand gases onto the surface
from inside the planet.from inside the planet.
Volcanic activity involving theVolcanic activity involving the
extrusion of rock intends toextrusion of rock intends to
form mountains over aform mountains over a
period of time.period of time.
Volcanoes are found whereVolcanoes are found where
tectonic plates are eithertectonic plates are either
diverging or convergingdiverging or converging..
• A volcanic eruption is when aA volcanic eruption is when a
volcano erupts and lets out lava,volcano erupts and lets out lava,
rocks, ash, and many more things.rocks, ash, and many more things.
• These things that are let outThese things that are let out
during a volcanic eruption areduring a volcanic eruption are
from the inside of the planet.from the inside of the planet.
• Volcanoes can form where thereVolcanoes can form where there
is stretching and thinning of theis stretching and thinning of the
planet’s crust or surface.planet’s crust or surface.
• Wildfires are common inWildfires are common in
different parts of thedifferent parts of the
world and they happen inworld and they happen in
• They are useful in theThey are useful in the
wilderness sometimeswilderness sometimes
because the effects of thebecause the effects of the
fires help some speciesfires help some species
with growth andwith growth and
• Nine out of ten wildfiresNine out of ten wildfires
are caused by humansare caused by humans
Wildfires are when fire isWildfires are when fire is
spreading quickly. A wildfire isspreading quickly. A wildfire is
a fierce fire that spreadsa fierce fire that spreads
rapidly and mostly in an arearapidly and mostly in an area
of wildernessof wilderness
A wildfire is any uncontrolledA wildfire is any uncontrolled
fire which occurs infire which occurs in
wilderness, wild lands, orwilderness, wild lands, or
Another word to say wildfire canAnother word to say wildfire can
be bushfire, hill fire, and manybe bushfire, hill fire, and many
more things can be the samemore things can be the same
meaning as a wildfire.meaning as a wildfire.
Wildfires means somethingWildfires means something
furious or destructive.furious or destructive.
Tsunami is a Japanese word meaning ‘harbor wave’. It isTsunami is a Japanese word meaning ‘harbor wave’. It is
constituted with two syllables, Japanese language meaningconstituted with two syllables, Japanese language meaning
harbour ("tsu",harbour ("tsu", 津津 ) and) and wavewave ("nami",("nami", 波波 ).).
Tsunami is a wave train or series of waves generated, byTsunami is a wave train or series of waves generated, by
impulsive disturbance that vertically displaces the water column,impulsive disturbance that vertically displaces the water column,
in water body. Earthquake, landslides, volcanic eruption,in water body. Earthquake, landslides, volcanic eruption,
explosion and even the impact of cosmic bodies like meteoritesexplosion and even the impact of cosmic bodies like meteorites
commonly generate tsunami. Tsunami savagely attacks coastlinescommonly generate tsunami. Tsunami savagely attacks coastlines
causing devastating property damage and loss of lives.causing devastating property damage and loss of lives.
Tsunami can be generated when the see floor abruptly deforms and verticallyTsunami can be generated when the see floor abruptly deforms and vertically
displaces the overlying water.displaces the overlying water.
Tectonic earthquakes are a particular kind of earthquake that are associatedTectonic earthquakes are a particular kind of earthquake that are associated
with the earth’s crustal deformation, when these earthquakes occur beneathwith the earth’s crustal deformation, when these earthquakes occur beneath
the see, the water above the deformed area is displayed from its equilibriumthe see, the water above the deformed area is displayed from its equilibrium
Waves are formed as the displaced water mass, which acts under the influenceWaves are formed as the displaced water mass, which acts under the influence
of gravity, attempts to regain its equilibriumof gravity, attempts to regain its equilibrium
• Droughts are long period of extremely dry weather when there
is not enough rain for the successful growing of crops or the
replenishment of water supplies.
• Floods are water covering previously dry area.
• A flood is a very large amount of water that has overflowed
from a source such as a river, lake, and ocean.
• They can also have overflowed a broken pipe onto a previously
• The damages after a flood is harsh because everything or parts
of things will be under water and the effects of a flood can kill
Kinds Of Floods
Flooding can also be divided into different categories according to
Coastal Floods usually occur along coastal areas. When there are
hurricanes and tropical storms which will produce heavy rains, or giant
tidal waves created by volcanoes or earthquakes, ocean water may be
driven onto the coastal areas and cause coastal floods.
This is the most common type of flooding. When the actual amount of
river flow is larger than the amount that the channel can hold, river
will overflow its banks and flood the areas alongside the river. And
this may cause by reasons like snow melt or heavy spring rain.
In most of the urban area, roads are usually paved. With heavy rain,
the large amount of rain water cannot be absorbed into the ground and
leads to urban floods.
There are many disruptive effects of flooding on human settlements
and economic activities. However, floods (in particular the more
frequent/smaller floods) can bring many benefits, such as recharging
ground water, making soil more fertile and providing nutrients in
which it is deficient. Flood waters provide much needed water
resources in particular in arid and semi-arid regions where
precipitation events can be very unevenly distributed throughout the
year. Freshwater floods in particular play an important role in
maintaining ecosystems in river corridors and are a key factor in
maintaining floodplain biodiversity
Massive amounts of erosion can be
accomplished by flood waters. Such
erosion can undermine bridge
structures, levees, and buildings
causing their collapse.
Flooding of farmland usually
results in crop loss. Livestock,
pets, and other animals are
often carried away and drown.
Water entering human built
structures cause water damage. Even
with minor flooding of homes,
furniture is ruined, floors and walls
are damaged, and anything that
comes in contact with the water is
likely to be damaged or lost.
Flooding of automobiles usually
results in damage that cannot easily
Transportation systems may be
disrupted, resulting in shortages
of food and clean-up supplies.
Food grains stored at home or in
go-downs get wet and start
rotting. In under developed
countries food shortages often
lead to starvation
Gas and electrical service may be
disrupted. Water supply pipes/
system get damaged and wells get
inundated creating shortage of
The affected communities living
in temporary shelters/
resettlements have limited or no
access to safe drinking water,
food etc. In addition, prevailing
unhygienic sanitary conditions
make it conducive for spread of
food and waterborne diseases.
• Hurricanes are several tropical storms that can form in
the Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and in
the Pacific Ocean.
• Hurricanes gather heat and energy through contact with
warm ocean waters.
• Hurricanes are named so people can spot and identify them
while they move across the ocean.
• Hurricanes that occur at the seas, and oceans cause large
waves, heavy rain, and high winds. These things can cause
destruction to international shipping and may cause many
• Tropical cyclones is another name for hurricanes when it is
at a certain level or at a certain size.
• Some hurricanes that have occurred are the Bombay
Hurricane in 1882 in India, and Hurricane Katrina which
happened in the United States.
Lighting storms and
• Lighting storms and
thunderstorms are basically
the same thing.
• They both contain flashes of
lighting striking an area and
the effects of the lighting
• Sometimes during these
storms, it also rains, snows or
hails in certain cases.
• A lighting is caused when a
electrical charge is contained
in a cloud and then releases it
on the earth’s surface. The
temperature of a lighting
bolts is extremely hot.
• Tornadoes can happen when
there is a thunderstorm. The
color of tornadoes ranges from
shades of gray, shades of
brown, and white. Some times
they are not that visible to see.
• A tornado is a dangerous
rotating column of air which is
connected to the surface of the
earth and a clod. It destroys
anything it touches in its path.
• Tornadoes are extremely
rotating column of air that
passes in a narrow path over
• Tornadoes can come in many
sizes and shapes. The usual
shape of a tornado is a funnel,
which is seeable and is narrow
end touches the earth’s surface.
• A cyclone is a large-scale storm system with heavy rain and winds that
rotate counterclockwise in the Northern Hemisphere and clockwise in
the Southern Hemisphere around and toward a low pressure center.
• Cyclones have also been seen on other planets other then the Earth,
such as Mars, and Neptune.
• Some deadly cyclones that happened before are the Bhola cyclone in
Bangladesh in 1970, the India cyclone in India in 1839, the Calcutta
cyclone in India in 1737, and the Bangladesh cyclone in Bangladesh in
Hazard Management Activities
a. Disaster Mitigation
b. Natural Hazard Prediction
c. Emergency Preparedness
d. Disaster Rescue and Relief
e. Post-Disaster Rehabilitation and Reconstruction
f. Education and Training Activities
An accurate and timely prediction of a hazardous event can save human
lives but does little to reduce economic losses or social disruption which
can only be accomplished by measures taken longer in advance.
Mitigation of disasters usually entails reducing the vulnerability of the
elements at risk, modifying the hazard-proneness of the site, or changing
Natural Hazard Prediction
The prediction of a natural event can be done by scientific investigation
into its causes and ensures establishing the probability of the next
occurrence in terms of time, place, and range of severity. Increasingly
sophisticated monitoring stations, both manned and remote, collect
information of potentially hazardous events for more accurate
Some hazards, such as hurricanes and floods, can be forecast with high
accuracy, whereas it’s very difficult to forecast earthquakes or
volcanoes or landslides.
Emergency preparedness is aimed at minimizing the loss of life and
property during a natural event. Preparedness includes actions taken
in anticipation of the event and special activities both during and
immediately after the event.
Two levels of preparedness
Public safety information
Hazard awareness planning
Disaster Rescue and Relief
After a natural calamity, local residents usually undertake the first
relief activities. However, their efforts must usually be complemented
with those of national or regional authorities. The main activities of
post-disaster relief include the preparation of lifelines or critical
facilities for emergency response, training, disaster rehearsals, and the
identification and allocation of local and external resources.
Post-Disaster Rehabilitation and Reconstruction
Post-disaster rehabilitation is carried out to restore the normal
functions of public services, business, and commerce, to repair
housing and other structures, and to return production facilities to
Education and Training Activities
Education and training, both formal and informal, prepare people at
all levels to participate in hazard management. Universities, research
centers, and international development assistance agencies play the
leading formal role in preparing individuals to face natural hazards.
These activities are also carried out by operational entities such as
ministries of agriculture, transportation, public works, and defense.