NCERT Solutions for Class 5 EVS Chapter 14

Natural disaster is a sudden natural event that causes a massive loss of life, property. It is thus a natural calamity often causing sudden, extensive and serious damage to life and property. Earthquakes, Tsunamis, Volcanic eruptions, Floods, Droughts, Cyclones, Landslides and Forest fires are forms of natural disasters.

An earthquake is a sudden movement or a violent shaking of earth due to the movement of the tectonic plates in the earth’s crust which causes a great destruction. An earthquake is thus an intense shaking of Earth’s surface. The shaking is caused by movements in Earth’s outermost layer.

i. Seismograph is an instrument used to measure and record the earthquake tremors or movements.
ii. Seismology is the scientific study of an earthquake.

The Richter scale which is also called the Richter magnitude scale or Richter’s magnitude scale. It is a measure of the strength of earthquakes. It was the first scale developed by Charles Francis Richter in 1935. He called it the “magnitude scale “as it was used for measuring the magnitude or intensity of an earthquake.

A flood is an overflow of a large amount of water beyond its normal limits. Flood is actually sudden flooding of water in low lying dry areas due to heavy rain. During rainy season many parts of India get flooded. Flood cause damage to roads, buildings and crops.

Drought is a prolonged dry period when there is no rainfall for several years which leads to drying of crops is called drought. This results in no food for the people which causes famine in which the people die of hunger.

Focus is a place where an earthquake originates. The focus of an earthquake is the point where the rocks start to fracture. It is thus the origin of the earthquake.

Epicentre is the centre point which is above the focus of an earthquake. It is the point on the Earth’s surface directly above the focus.

The flood is caused due to-
• Heavy and continuous rainfall in a particular area as a result of which the water level in the river keeps rising. When the rivers are not able to hold excess water, the excess water flows over the river bank and floods the surrounding areas.
• Collapse of a wall of the dam
• rapid melting of the snow or a storm surge from a tropical cyclone or tsunami in coastal areas.

Why does an Earthquake Occurs?
Ans. An earthquakes occurs when two large pieces of the earth’s crust suddenly slip. When this slip takes place, there is movement of massive energy through the earth in the form of waves, which we feel and call an earthquake.
Earthquakes are the deadliest of all the natural disasters. Strong earthquake can destroy entire city. Over 10,000 people die every year in earthquakes.
The place on the surface of the earth where the earthquake is strongest is called epicentre. Therefore, places close to epicentre suffer maximum damage.

A drought is caused due to:
• low precipitation or rainfall over an extended period of time.
• Atmospheric conditions such as climate change,
• changes in ocean temperatures,
• changes in the jet stream, and
• changes in the local landscape are all factors that contribute to drought.
• Lesser growth of plants

The effects of a flood are as follows:
• loss of human life,
• property damage,
• destruction of crops, livestock loss and
• waterborne diseases, caused by stagnant water like cholera, typhoid etc.

The following measures should be kept in mind in regards to floods-
• Keep the first aid kit ready for any kind of emergency
• Keep food and clothes ready in a water proof bags
• Grow more and more trees to prevent water loss
• Build special dams to control the speed of water as well as excess water
• Keep stocks of food and water handy.

The effects of a drought are as follows:
• Extreme scarcity of water and food which might result in a famine
• Loss of life
• Crops get effected as no water availability
• Hunger and starvation leading to death

During an earthquake, there is every possibility of a collapse of a house. Moreover, it may also be difficult for us to run out of the building during an earthquake So, at that particular time we need to hide under something strong to avoid getting injured due to a collapse.

Animals like dogs have super sense of hearing which helps them to feel the vibrations of the shaking ground or sensing an earthquake. They can forewarn us about the disaster. They can use their super sense of smell in finding the people who are trapped under the debris sfter an earthquake or some other calamity.

On 26th January, 2001 an earthquake occurred in Gujarat which had an intensity of 6.9 on the Richter Scale.

During a disaster, the government has a crucial role. It does the following things:
• The Indian Armed forces are trained to help in these difficult situations
• They drop the packets of food, clothes, water packers and medicines in the affected areas.
• The red cross society supplies urgent medical relief.
• NCC also helps the people affected at the disaster sites
• FAO, ILO, WHO and NGOS also help at the time of a disaster.
• Search and rescue operations are also conducted to find out the people trapped in the debris.

Cyclones are strong and rotating winds that are common in coastal areas and are associated with high tides and floods. Cyclones last from several hours to more than 2 weeks over open waters. It is thus a storm or system of winds that rotates about a centre of low atmospheric pressure and that moves forward at a speed of 20 to 30 miles (30 to 50 kilometres) an hour and often brings heavy rain.

Landslides are common in hilly region. They occur when slippery mosses of rock, earth and debris slide down the mountain slope due to heavy rain fall or earthquake. It is a large amount of earth, rock, and other material that moves down a steep slope and happens when a layer of earth or rocks separates from the layer below it. The force of gravity pulls the loose layer downward. A landslide needs a steep slope to get its start.

A Volcano is a hill with a vent which reaches down to the hot molten rock below the surface of the earth. During a volcanic eruption the molten rock is forced up the vent which comes out of the top as Lava. The Lava flows out very fast and burns everything that comes in its way. It causes great damage to property and life. A volcano is thus an opening in the earth’s crust through which lava, volcanic ash, and gases escape.

A volcano can be active, dormant and extinct.
An active volcano is a volcano which has a history of recent eruptions; they are likely to erupt again. Inside an active volcano is a chamber in which molten rock, called magma, collects.
A dormant volcano is the one which has not erupted for a very long time but may erupt at a future time.
An extinct volcano is the one which is not expected to erupt in the future.

Sometimes a fire breaks out in a forest due to lightning or due to dry leaves and twigs rubbing against one another. This is called forest fire. Forest fires are large uncontrolled fires that take place in the forest. Some of the severe fires occur in the forest because there is so much fuel (trees) to burn. Forest fires are a type of wildfire.

The outer surface and inner core of the Earth are totally different in their nature and structure.
The structure of the Earth’s interior is divided into three layers namely the crust, the mantle and the core.
• Crust: Crust is the outer layer of the Earth, where we live. It is the solid and rigid layer of the Earth.
• Mantle: The interior part beneath the crust is called mantle, which is about 2,900 km thick. In the upper part of the mantle, the rock remains solid, whereas in the lower part of the mantle, rocks are in molten form. This molten rock inside the Earth is called ‘magma’.
• Core: The core is the innermost and hottest layer of the Earth which lies below the mantle. It is composed mainly of Nickel (Ni) and Iron (Fe). Hence it is called NIFE. The core is divided into Solid inner core and Liquid outer core.

Scientists have been able to understand the Earth’s interior by studying the seismic waves. The Seismic waves travel at different speeds when they pass through different types of material. So, by studying seismograms, scientists are able to learn a lot about Earth’s internal structure.

Engineers and architects suggest people to build new houses with special designs which will save their houses from earthquake. These houses will be safer if there is an earthquake again as these houses are built with special designs suggested by the engineers.

The following organizations provide help and relief in disaster effected areas:
• American Red Cross – Volunteers help provide disaster relief, including clean water, hot meals, and shelter to families and communities.
• National Voluntary Organizations Active in Disaster (NVOAD) assists communities affected by disasters.
• International Relief Teams.
• International Rescue Committee.
• UNICEF

Famine is a widespread condition in which most of the people of a country or region are not able to get adequate food supplies. Famines result in malnutrition, starvation, disease, and high death rates. It is the scarcity of food, caused by factors like war, inflation, crop failure, population imbalance, or government policies.

A Mock Drill is a practice session conducted to ensure the effectiveness of the plan before it is executed, so that the organization is prepared to face the disaster if happens. It is the testing of the effectiveness of Disaster Management Plan.
A plan has to be prepared and then a mock drill is conducted which may last only a few minutes. It is a participating method to practice the safety-related measures and evacuation of a building during an emergency situation.

The objective of mock drill is to analyse the emergency preparedness plan of the organization or the country and evaluate the standard operating procedure, so that concerned persons could deliver their duties successfully while keeping in an understanding of life and property.

In case of an earthquake a person should not go outside during an earthquake as we could get severely injured, or even buried, by falling debris (an air-conditioner, a balcony, a wall). If you live on the ground floor, then immediately move out from your house and stay in open grounds If we are near an outer wall of the building, we should move towards the interior, but no more than a few steps. Then follow the “drop, cover, hold on” method.
Whenever an earthquake strikes, make sure you stay in bed instead of running around. Try covering your head with a pillow to protect yourself. If you are running downstairs make
sure you use stairs and not lifts.

Drop, cover and hold during an earthquake means-
• DROP where ever you are, on your hands and knees. This position will protect you from getting knocked down and also allow you to stay low and crawl to shelter if nearby.
• If you take cover under a durable and strong piece of furniture.
• HOLD on to it and be prepared to move with it. Hold the position until the ground stops shaking and it is safe to move.

On 26th January 2001, an earthquake struck the Kutch and Bhuj area of Gujarat nearly at 10:30 a.m. Many hundred people were killed and thousands were injured. Army jawans were called for help. Nearly 150 buildings were collapsed. There was really a great destruction all around. The government did its best to relocate the people.

Man-made disasters are dangerous unsafe events that are caused by activities of human beings. Some examples of man-made disasters are chemical spills, explosions, chemical or biological attacks, nuclear blast, train accidents, plane crashes, or groundwater contamination.

Tsunami is a long and high sea wave caused by an undersea earthquake which results in a huge oceanic wave. This wave moves towards the land and leads to a major damage as well as disturbance there.