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General Knowledge · Class 10 · Geography and India

Earthquakes, cyclones and floods

In 1999 a super cyclone in Odisha killed about 10,000 people. In 2013 Cyclone Phailin, just as strong, killed fewer than 50. What changed?

Small test at the end: scroll down to the end of this page for five short questions that check what you have learnt. Tap an answer, then press Check answer. Go to the questions ↓

Jump to: Read first · Try it away from the screen · Check it yourself · Check yourself · For teachers

Read first

5 facts. The questions below make you use them, not just remember them.

  1. Earth's outer layer is broken into plates. The Indian plate pushes into the Eurasian plate by about 5 cm a year, raising the Himalayas and causing earthquakes in the north and north-east.
  2. On the magnitude scale, each whole step up means about 32 times more energy. Bihar was hit hard by the 1934 earthquake of about magnitude 8, and shaken by the 2015 Nepal earthquake.
  3. Cyclones form over warm seas. Better forecasts, cyclone shelters and moving people early meant that about a million people were evacuated before Phailin hit Odisha in 2013.
  4. The Kosi river carries huge amounts of silt and often changes its course. In 2008 it broke its banks and flooded north Bihar. It has long been called the "Sorrow of Bihar".
  5. In an earthquake, the safest action indoors is "Drop, Cover, Hold on": get down, take cover under a strong table, and hold on until the shaking stops.

Offline

Try it away from the screen

With your family, make a simple emergency plan: where to meet, a list of phone numbers on paper, and a bag with water, a torch and medicines. Practise "Drop, Cover, Hold on" once.

Make it on paper. Keep it with you. Nothing to upload.

Check it yourself

During disasters, false messages spread fast ("dam has burst", "big quake tonight"). Earthquakes cannot be predicted to the day. Check alerts from the India Meteorological Department or the National Disaster Management Authority.

Check yourself

Five questions about what this page teaches. Choose an answer and press Check answer, or open "See the answer and why". Nothing is saved or sent: your choices stay on this screen and disappear when you leave or reload the page.

  1. Question 1 of 5What causes most earthquakes in the Himalayan region?

    See the answer and why
    • A. Heavy snow pressing down on the mountains Not this one. Snow is far too light to cause earthquakes.
    • B. Volcanoes erupting under the mountains Not this one. The Himalayas have no active volcanoes.
    • C. The Indian plate pushing into the Eurasian plate Correct. Yes. Stress builds up and is released as earthquakes.
    • D. Strong winds shaking the ground Not this one. Wind cannot shake the solid ground like that.
  2. Question 2 of 5A magnitude 8 earthquake releases about how many times more energy than a magnitude 6? (Each whole step is about 32 times.)

    See the answer and why
    • A. 1,024 Correct. Yes. Two steps: 32 × 32 = 1,024 times.
    • B. 64 Not this one. That adds 32 twice. Each step multiplies.
    • C. 2 Not this one. The numbers differ by 2, but each step is 32 times more energy.
    • D. 2,048 Not this one. Check: 32 × 32 is 1,024.
  3. Question 3 of 5Why did Cyclone Phailin in 2013 kill far fewer people than the 1999 super cyclone?

    See the answer and why
    • A. It missed the land completely Not this one. Phailin made landfall near Gopalpur, Odisha.
    • B. Phailin hit the coast at night when everyone was asleep and safe indoors Not this one. Being asleep indoors is not safe in a strong cyclone. Evacuation was.
    • C. Phailin was a much weaker storm Not this one. Phailin was also a very severe cyclone with very strong winds.
    • D. Early warnings, shelters and evacuating about a million people Correct. Yes. Preparation saved thousands of lives.
  4. Question 4 of 5The ground starts shaking while you are in a classroom. What should you do?

    See the answer and why
    • A. Run down the stairs at once Not this one. Running during shaking causes falls. Wait until it stops.
    • B. Stand by the windows to see outside Not this one. Glass can shatter. Stay away from windows.
    • C. Use the lift to get out faster Not this one. Never use a lift in an earthquake.
    • D. Drop, take cover under a desk and hold on Correct. Yes. Most injuries come from falling objects.
  5. Question 5 of 5Why is the Kosi called the "Sorrow of Bihar"?

    See the answer and why
    • A. It dries up completely every year Not this one. The Kosi carries a lot of water, especially in the monsoon.
    • B. Its water is too salty to use Not this one. It is a freshwater river from the Himalayas.
    • C. It is the coldest river in India, fed by glaciers Not this one. Its name comes from the floods, not its temperature.
    • D. It often changes course and causes floods Correct. Yes. Its heavy silt load blocks its own channel.

For teachers and grown-upsWhere the facts come from, and how to use this round.

Sources and notes
  • Odisha super cyclone: October 1999. Phailin: 12 October 2013 (IMD, OSDMA). Kosi breach at Kusaha, 18 August 2008.
  • NDMA school safety guidelines recommend "Drop, Cover, Hold on". Magnitude energy factor about 31.6 per unit.
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