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Std 8 General Science · Chapter 9

9. Disaster Management

Complete solutions to the Exercises. Maharashtra State Board (Balbharati), Grade Eight General Science.

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Exercises

1Answer the following in your own words.

(a) Explain the relation between continuous rains and landslide. Give reasons.

  1. During continuous rain, water enters the cracks of rocks on hill slopes.
  2. The rocks become weak and loose.
  3. The soil and rocks absorb water and become heavy.
  4. Water reduces the friction between the layers.
  5. So the heavy mass of soil and rocks slides down the slope. This is a landslide.

Thus, continuous rain causes landslides.

(b) Prepare a chart showing ‘Do’s’ and ‘Don’ts’ at the time of earthquake.

Do’sDon’ts
Stay calm.Do not panic or run here and there.
Take shelter under a strong table or bed.Do not stand near windows or heavy objects.
Use the staircase to come out.Do not use the lift.
If outside, stay in an open place.Do not stand near tall buildings, trees or electric poles.
Switch off the main electric supply.Do not use candles or matchboxes.

(c) What are the specifications of an earthquake-proof building?

  1. It is built according to the codes of the Indian Standards Institution (IS 456, IS 1893, IS 13920).
  2. Its foundation is kept separate from the surrounding land.
  3. Base isolators are used below the building.
  4. Its design is simple and symmetrical.
  5. Good quality material is used.
the ground shakes to and froBuildingBase isolators(rubber-lead bearings)FoundationThe building sways far less than the ground under it

The foundation of an earthquake resistant building rests on base isolators, so the building sways much less than the ground.

(d) Explain the effects of landslide.

  1. Rivers get blocked and may change their paths.
  2. Waterfalls get displaced.
  3. There is a great loss of life and property.
  4. Roads and railway lines are blocked.
  5. Plants on the slope are destroyed.

(e) Is there any relation between dam and earthquake? Explain.

Yes. A big dam stores a huge amount of water. Its weight puts stress on the rocks below. Water also enters the cracks in rocks. So the rocks may move and cause an earthquake.

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2Give scientific reasons.

(a) It is safer to find shelter under things like a bed, table at the time of earthquake.

During an earthquake, roof pieces, fans and heavy objects fall down. A strong bed or table protects us from these falling objects. Hence, it is safer to take shelter under them.

(b) In monsoon, don’t take shelter near hillside.

In monsoon, rain water makes the rocks and soil on the hill loose and heavy. So landslides may occur. A person near the hillside may get buried. Hence, we should not take shelter near a hillside.

(c) Don’t use lifts at the time of earthquake.

Electric supply may fail during an earthquake. The lift may stop in between and people get trapped. The lift may also fall. Hence, lifts should not be used.

(d) The foundation of earthquake-proof building is separated from other land.

If the foundation is separated, the shaking of the ground does not pass fully to the building. So the building is not damaged. Hence, the foundation is kept separate from the land.

3If a crowd gathers at the place of earthquake, what would be the difficulties in relief work?
  1. Ambulances and rescue vehicles cannot reach the place.
  2. Rescue workers cannot work freely.
  3. The injured cannot be shifted quickly to the hospital.
  4. Rumours spread and cause confusion.
  5. People in the crowd may get hurt if walls fall.
4Make a list of the institutes and organizations who provide help for disaster management. Collect more information about their work.
  • National Disaster Management Authority (NDMA): Makes plans and policies for disaster management.
  • National Disaster Response Force (NDRF): Does rescue and relief work at the place of disaster.
  • Fire brigade and police: Put out fires, rescue people and control the crowd.
  • Army, Navy and Air Force: Help in rescue and shifting people to safe places.
  • Indian Red Cross Society: Provides first aid, food, clothes and medicines.
  • Home Guards, NCC and NSS: Help in first aid and relief work.
5Make a survey of your school according to the plan of disaster management and write the pointwise information.

Note the following points for your school:

  1. Primary information: Name, address and contact number of the school and Head Master.
  2. Disaster management committee of the school.
  3. Information about the school building: number of rooms, type of roof and age of the building.
  4. Information about the school ground and its distance from the main road.
  5. Daily routine of the school.
  6. Possible hazards in the school.
  7. Disaster management map of the school showing safe places.
  8. Mock drill held every month.
6Are there any possible places of landslide in your area? Collect information from experts.

Landslides may occur at the following places:

  • Steep hill slopes with loose rocks.
  • Ghat roads where hills are cut.
  • Slopes where trees are cut.
  • Quarry and mining areas.

Write your report after talking to experts in your area.

7With the help of the following picture, explain your role in the disaster management. (A student is thinking, “I am at risk…!”)

Before the disaster:

  • I will take part in mock drills.
  • I will learn first aid.
  • I will keep emergency numbers like 112, 108 and 101 ready.

During the disaster:

  • I will stay calm.
  • I will go to a safe place and help others.
  • I will not spread rumours.

After the disaster:

  • I will help in relief work.
  • I will give correct information to rescue workers.
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