Notes on Natural Disaster | Grade 7 > Science > Environmental Degradation and Its Conservation | KULLABS.COM

Natural Disaster

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Natural Disasters

Natural Disasters are extreme, sudden events caused by the environment that cause huge loss of life and property. Some of the examples of natural disasters are earthquake, volcano, landslide, flood, etc. The natural disasters like flood, landslide, soil erosion, etc occur frequently in Nepal. Many lives and property are damaged due to this. In this note, we discuss the earthquake and volcano with their causes, effects and safety measures.

Earthquake

Earthquake is the sudden movement of earth's surface caused due to the sudden release of energy in the earth's surface. It is the vibration of the earth's surface. The vibration may be left and right or up and down. There is a high possibility of the earthquake in Nepal. Nepal lies in the active earthquake region. Currently, a devasting earthquake of 7.9 Richter scale magnitude hit Nepal in 2015 AD. More than 10, 000 people died during this earthquake. Nepal was also hit by the devastating earthquake in 1990 BS and 2045 BS. The earthquake of 1990 BS killed 8519 people and earthquake of 2045 BS killed 721 people and damaged about 65, 000 houses and buildings.

Source: www.ibtimes.co.uk Fig: Eathquake, Nepal
Source: www.ibtimes.co.uk
Fig: Earthquake, Nepal

Causes of Earthquake

  • When there is the movement of tectonic plates present beneath the earth's surface, the earthquake occurs.
  • The earthquake occurs due to explosions during the extraction of minerals.
  • When there are contraction and relaxation of rocks beneath the earth's crust, the earthquake occurs.
  • The volcanic eruption also causes the earthquake.

Effects of Earthquake

  • It causes huge loss of life and properties.
  • It may cause flood and landslide.
  • It destroys water pipes, electric cables, communication lines, sewage pipes, canals, etc.
  • The earthquake under the ocean may cause the tsunami.
  • The earthquake also destroys water resources.
  • Plain surfaces may change into hills and mountains and hills and mountains may change into plain surface due to the earthquake.

Preventive and SafetyMeasures of Earthquake

  • Awareness programs should be conducted about the effects of the earthquake.
  • We should build earthquake resistant houses, buildings, bridges etc.
  • We should keep necessary things like first aid box, radio, torch light, dry food. drinking water, etc. for emergency use.
  • We should not stay near weak walls, electric cables, poles, buildings, etc.
  • We should help other disabled people during the earthquake.
  • We should stay in a safe place with patience until the shaking stops and listen to the broadcast from radio by the government.
  • We should turn off gas stoves, electric switches, water supply as soon as possible.
  • We should stay safely in one place during the earthquake.

Volcano

A volcano is a vent or crack in the eath's crust through which lava, ash, rock and gases erupt. The metals and rocks are found in the molten state in the mantle of the earth as it is very hot. This molten mass is known as magma. When the magma comes out in the earth crust through weak cracks or parts, it is then called lava. Lava is very thick. They move very slowly. Along with rocks, ash and bits fragmented lava and pumice also come during the volcano eruption.

Source; www.youtube.com Fig: Volcano
Source; www.youtube.com
Fig: Volcano

Causes of Volcano

  • When hot magma from the eath's surface flows through the cracks in the rocks to the surface of the earth, volcano occurs. When the water from the earth's surface enters the mantle through these cracks, the water evaporates and creates pressure because of which the magma flow up through these cracks which are known as volcanic eruption.
  • During the shifting of tectonic plates, cracks or fissures are formed in the earth's crust. The molten mass inside the earth erupts through these cracks or fissures.

Effects of Volcano

  • It causes huge loss of life and property.
  • Volcanic ash and gases cause air pollution.
  • It destroys man- made physical infrastructures and other animals.
  • It covers forests, fertile lands, crops, etc.
  • The structure of the earth may change due to the volcano.
  • There is a high chance of tsunami if volcano eruption occurs near the sea.



  • Natural disaster causes huge loss of life and property.
  • The sudden shaking of the earth's surface is called an earthquake.
  • Earthquake occurs due to the sudden release of energy in the earth's surface.
  • A volcano is a place on the earth's surface where molten rocks, gases and debris erupt through the earth's crust.
  • Volcano brings changes in the structure of the earth's surface.
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Very Short Questions

The sudden shaking of the earth's surface is called an earthquake. Any three causes of earthquake are given below,

  • The earthquake occurs due to the volcano eruption.
  • It occurs due to contraction and relaxation of rocks beneath the earth's crust.
  • The earthquake also occurs due to explosions during the extraction of minerals.

Any three effects of  the earthquake are given below,

  • The earthquake causes huge loss of life.
  • The earthquake destroys water resources.
  • The earthquake may cause flood and landslide.

Any three safety measures of Earthquake are given below,

  • We should stay away from weak walls, electric cables, and tall buildings.
  • We should turn off switches, gas stoves and water supply as soon as possible.
  • We should help disabled people.

A volcano is a place on the earth's surface where molten rocks, gases and debris erupt through the earth's crust. When hot magma from the eath's surface flows through the cracks in the rocks to the surface of the earth, volcano occurs. When the water from the earth's surface enters the mantle through these cracks, the water evaporates and creates pressure because of which the magma flow up through these cracks which are known as volcanic eruption.

Any three effects of volcano are given below,

  • Ash and gases coming out from volcano cause air pollution.
  • It brings changes in the structure of the earth's surface.
  • It kills people and destroys property.

0%
  • The sudden shaking of the earth's surface is called

    Landslide
    Volcano
    Earthquake
    Movment of earth
  • How many people were killed in devastating earthquake of 1990 BS?

    7585 people
    654 people
    8519 people
    5689 peope
  • How many people were killed in devastating earthquake of 2045 BS?

    721 people
    985 people
    456 people
    658 people
  • Which one of the following is not the effect of earthquake?

    Cause flood and landslide
    Destroys electric cables, water pipes etc
    Saves life of people
    Destroy water resources
  • The temperature of the mantle of the earth is

    cold
    Very low
    Normal
    Very high
  • The metals and rocks in the mantle are found in molten state which is known as

    Lava
    Magma
    Crack
    Ash
  • Which one of the following natural disaster is not caused by earthquake?

    Flood
    Landslide
    Tsunami
    Hurricane
  • Volcano eruption near the sea creates

    Soil erosion
    Volcano
    Tsunami
    Landslide
  • Earthquake may occur due to

    Soil erosion
    Deforestation
    Volcanic eruption
    Flood
  • Which one of the following is not the natural disaster?

    Volcano
    Deforestation
    Landslide
    Flood
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Theawesomenator

What is the worst natural disaster


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Flood

Short note about flood


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