12 Natural Disasters
Nature
is very powerful. It provides us with everything. Sometimes, calamities are
caused by nature. Such calamities are called natural disasters. Earthquakes,
tsunamis, floods, droughts, landslides, volcanic eruptions, cyclones, etc. They
cause damage to life and property. Although we cannot prevent them, yet our
preparedness can save us from their disastrous impact.
Let
us read about some natural disasters and the precautions we need to take.
Earthquake
Our
Earth's crust is based on tectonic plates. These plates are in constant motion
as they are on the Earth's mantle which is made of molten rocks. Whenever these
plates collide with each other, major or minor earthquakes occur. Earthquakes
are a regular activity. Most of the time, the earthquakes are so minor that
they are not felt by us. However, when the collisions are of greater intensity,
earthquakes are felt strongly.
Destruction
caused by an earthquake
The
point where the earthquake starts is called the focus. The point on land directly
about the focus is called the epicentre. The earthquakes are most intense at
the epicentre. High magnitude or high intensity earthquakes can turn huge
buildings into rubbles in a few seconds. The earthquake in Nepal in 2015 caused
untold misery to people.
Seismograph
is used for measuring and recording an earthquake. Scientists use the Richter
Scale for measuring the intensity of an earthquake.
Precautions
Run
out of the building immdediately. Stand away from buildings, lamp posts, etc.
During
an earthquake, one should not stand near the outer walls or windows.
If
it is not possible to get out of the building, one must take cover under heavy
furniture.
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There can be equally devastating aftershocks. So one should not enter the
building immediately after an earthquake.
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Regular drills to make people aware of the Dos and Don'ts during an earthquake
must be carried out in schools and offices.
Tsunami
Tsunami
is a Japanese term meaning 'harbour waves'. There can be many reasons for
tsunamis like underwater earthquakes, volcanic eruptions or high intensity
underwater explosions. Tsunami comes when the seabed is disturbed. It displaces
large amounts of water. Tsunamis only come in the coastal areas. The huge waves
carry massive quantities of water and they can travel much further inside the
coast posing a threat to life and property. The fearful tsunami in the Indian
Ocean in 2004 affected 14 countries including our country, and claimed more
than 2,30,000 lives.
Precautions
People
living in coastal areas must listen to the tsunami warnings and never ignore
them.
They
should not go into the sea or near the coast.
People
should be shifted from low-lying coastal areas to higher grounds.
Volcanoes
When
the magma under the Earth's crust spills over on its surface, it is called a
volcanic eruption. The molten magma under the pressure of heat keeps thrusting
the crust. When it gets a weak surface, it makes an opening there. The magma
that comes out of the Earth is called lava. Huge amount of ash, molten rocks in
the form of lava and gases erupt from a volcano through a vent. When a volcanic
eruption cools off, it takes the shape of a mountain; the bowl-shaped hollow
formed at the top is called a crater.
Volcanic
eruption
Although
the volcanoes have a very long life span, ranging from a few years to hundreds
of years, we can classify them on the basis of their erupting histories and
frequencies into the following.
1.
Active volcanoes: The volcanoes that have erupted in the recorded history, or
which might erupt in the near future are called active volcanoes. Mount Etna in
Italy is an example of this type of volcano.
FAST
FACT
The
word 'volcano' comes of the Roman god of fire, Vulcan.
2.
Dormant volcanoes: The volcanoes which have not erupted for a long time but
have become active in the recent past are called dormant volcanoes. Mauna Kea
in Hawaii is an example of such volcano.
3.
Extinct volcanoes: These are volcanoes that have not erupted since long and
have shown no sign of any kind of activity. Mount Kilimanjaro in Africa is an
example of extinct volcano.
Precautions
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The known sites of recent volcanic activities should be avoided for habitation.
*
The signs of eruptions are visible much before the actual eruption. People
should immediately evacuate an area surrounding the volcano in such case.
People
should be made aware of the risks and the measures to be followed during the
evacuation procedure.
Floods
Sometimes
the water in the rivers overflows and moves into the dry lands and submerges
the land. This cause floods. Floods have been the most commonly known natural
calamity in human history.
Floods
generally occur when there is a heavy rainfall during monsoons, and when the
mountain snow melts on a large scale.
A
flooded area
Flash
floods occur when there is a cloudburst which causes heavy rainfall in a small
area. Another reason for flash floods is breaking of dams and barrages that
release massive quantity of water at once.
Floods
not only cause loss of life and property but also many waterborne diseases.
Shortage of clean drinking water, accumulation of street refuse in water,
floating remains of humans and livestock pose a severe health hazard in the
affected areas.
Precautions
•
Flood-prone areas should be built taking into consideration the inflow of water
during floods.
The
drainage system of such areas must he made more adaptive to floods, so that
water can be drained easily.
◆ Evacuation measures should be made adequate for such flood-prone
areas.
◆ Adequate quantities of food, water, medicines and other necessary
iterns should always be stocked for emergencies.
Drinking
water must be boiled before use.
Afforestation
is a mandatory precaution for the flood-prone areas.
Droughts
Drought
is another common natural calamity that causes severe and economic hardships
for humans. Drought is the extended period of lack of rain or water
replenishment. It can cause severe damage to agriculture, livestock and humans.
Precautions
Proper
reservoirs and water tanks need to be built and maintained to conserve water.
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Rainwater harvesting measures need to be implemented strictly in drought-prone
areas.
Cultivation
of drought-resistant crops such as maize, millets, etc. should be encouraged.
Water
storage structures, like dams, should be built in such areas to supply water in
times of drought.
Cyclones
When
a difference of high pressure and low pressure wind is created in the coastal
areas, it generally takes the form of cyclones. Cyclones are huge storms of
very high speed with a centre of low pressure surrounded by high pressure wind
which is rotating. These are accompanied by heavy showers and cause severe
damage to life and property.
Precautions
Early
warning systems should be installed in the cyclone-prone areas to warn people.
A
sateallite image of a cyclone
People
should move to safer places in times of cyclones.
Tree
plantation in such areas should be promoted as it helps in countering cyclones.
Buildings should be constructed keeping in mind the cyclonic activities.
Disaster
management
Natural
disasters are usually uncontrollable. We cannot prevent them. We can only be
saved by being prepared to avoid or counter them. Our preparedness can help us
to face natural calamities.
Disaster
management stands for a wide range of activities initiated to control disasters
or emergency situations. It includes steps right from creating awareness among
people and preparing them before a disaster to post-disaster activities such as
relief and rehabilitation.
Forewarned
is forearmed: If proper early warning systems are installed in areas prone to
natural disasters and people are adequately trained, then the risks of damage
could be minimised.
Inclusion
in elementary education: Children should be taught and trained in measures to
take during natural disasters through mock drills and exercises.
Formation
of emergency response teams: Emergency response teams would be better prepared
to respond quickly to emergencies like earthquakes, tsunamis, floods, cyclones,
etc., than other civic agencies.
Word
Bank
disaster:
an event that causes widespread death and destruction
tsunami:
very high waves in the sea caused by an earthquake or some other disturbance
intensity:
a measure of the amount of movement of the ground during an earthquake lava:
the mixture of molten and semi-molten rocks that come out during a volcanic
eruption
magma:
a mixture of molten and semi-molten rocks under the Earth's crust in the mantle
vent:
the mouth of the volcano from where lava comes out
crater:
the hollow area created by the volcanic eruption on the surface of the Earth
afforestation:
the process of planting trees in a barren land to convert it into a forest
rainwater harvesting: a procedure to store rainwater for reuse
In
a Nutshell
❖ There are
various types of natural disasters such as earthquakes, tsunamis, floods,
droughts, landslides, volcanic eruptions, cyclones, etc.
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A tsunami, the high harbour waves, caused due to underwater earthquakes,
volcanic eruptions or high intensity underwater explosions, has the capacity to
destroy everything in its path.
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Cyclones are huge storms of very high speed with a centre of low pressure
surrounded by high pressure wind which is rotating.
Disaster
management stands for a wide range of activities initiated to control disasters
or emergency situations.
Exercises
A. Circle the correct options.
1. Nuclear
explosion is not a natural disaster.
2.
The point where the earthquake starts is called focus.
3.
When the magma under the Earth's crust spills over on the surface, it is
called volcanic eruption.
4. Afforestation prevents floods.
B. Match the following.
|
Column A |
Column B |
|
Precaution against drought |
d. rainwater harvesting |
|
Overflow of river water |
e. flood |
|
Underwater volcanic eruption |
b. tsunami |
|
Vibrations on the surface of the Earth |
a. earthquake |
|
Violent storm of wind |
c. cyclone |
C. Fill in the blanks.
1. Seismograph is
used for measuring and recording an earthquake.
2. Rainwater
harvesting, building reservoirs and dams, and recycling of water are some
measures necessary to prevent drought.
3. Cyclones are
huge storms of very high speed with a center of low pressure surrounded by high
pressure wind which is rotating.
4. Floods
occur when the water in the rivers overflows and moves into the dry lands and
submerges the land.
5. The
three types of volcanoes are active, dormant, and extinct.
D. Answer the following questions in detail.
1. What are volcanoes? Describe the three types of
volcanoes.
Volcanoes are
openings in the Earth's crust through which molten rock, called magma, erupts.
When magma reaches the surface, it's called lava.
There are three main types of volcanoes based on
their eruptive activity:
·
Active volcanoes:
These volcanoes have erupted in recent history or are expected to erupt in the
near future.
·
Dormant volcanoes:
These volcanoes have not erupted in a long time but have the potential to do so
in the future.
·
Extinct volcanoes:
These volcanoes are not expected to erupt again.
2. What is disaster management? Suggest three ways of disaster
management.
Disaster management is
a comprehensive approach to dealing with natural or man-made disasters,
including prevention, preparedness, response, and recovery. It aims to minimize
the impact of disasters and promote resilience.
Here are three ways of disaster management:
·
Risk assessment:
Identifying potential hazards and assessing their vulnerability to different
areas.
·
Preparedness planning:
Developing emergency plans, training personnel, and stockpiling supplies.
·
Early warning systems:
Implementing systems to detect and alert people about impending disasters.
3. How does flood occur? What are its effects?
Floods
occur when the amount of water flowing into a river or other body of water
exceeds its capacity to hold it. This can be caused by heavy rainfall,
snowmelt, or dam failure.
Floods can have devastating effects, including:
·
Loss of life and property
·
Damage to infrastructure
·
Contamination of water supplies
·
Displacement of people
·
Spread of diseases
4. What precautions should be taken against tsunami?
·
Stay informed: Be
aware of tsunami warnings and evacuation routes.
·
Evacuate immediately: If
a tsunami warning is issued, move to higher ground as quickly as possible.
·
Stay away from the coast:
Avoid going to the beach or other coastal areas after a tsunami.
·
Build tsunami-resistant structures:
Construct buildings and infrastructure that can withstand the force of a
tsunami.
5. Suggest some measures to prevent droughts and famines.
·
Water conservation:
Implement water-saving measures in agriculture, industry, and households.
·
Rainwater harvesting:
Collect and store rainwater for use during dry periods.
·
Diversification of crops:
Plant crops that are more drought-resistant.
·
Early warning systems:
Monitor weather patterns and issue drought warnings.
·
Emergency food aid:
Provide food assistance to affected areas during times of drought.
E. Think and answer.
Why should we run out of an enclosed building during an
earthquake?
When an earthquake happens, it's best to go outside. Buildings can break apart, and you might get hurt by falling pieces. Going outside is safer because you won't be trapped or hurt by the
broken building.
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