Q. 1. What is a Tsunami ?

Ans. Tsunami (pronounced as soo-NAH-mee) is a Japanese term which has been universally adopted to describe a large seismically generated sea wave which is capable of considerable destruction in certain coastal areas, especially where submarine earthquakes occur.

Q. 2. Explain any five characteristics of a Tsunami.

Ans. Five main characteristics of a Tsunami are :
1. Usually an intense earthquake starts the Tsunami waves which start rolling across the sea.
2. At places where the ocean is deep tsunami can travel unnoticed on the surface at speeds more than 500 miles (or 800 kilometres) per hour.
3. In some places, the Tsunamis may rise to a few feet but at other places they may surge as high as 100 feet or more.
4. A tsunami is not a single wave but a series of waves, better known as a wave train.
5. Tsunamis possess enormous force. Heavy objects including large rocks weighing several tons, alongwith heavy boats are tossed around, being thrown several metres inland.


Q. 3. How are Tsunamis caused ?

Ans. 1. A Tsunami is generated by any disturbance that suddenly displaces a large mass of water. Such a disturbance may be caused by any of these : an underwater earthquake, landslide or volcanic eruption.
2. Sometimes, tsunamis are also caused whenever there is a sudden displacement of a part of the crust due to the movement of the tectonic plates below the surface of the sea.
3. On rare occasions a tsunami can be generated by a giant meteoric impact in the Ocean. Scientists believe that about 3·5 billion years ago an asteroid collision event may have created a great tsunami due to which the coastline of the continents was changed drastically and life on land was exterminated.


Q. 4. What are the impacts of a Tsunami ?
Is it true to say that tsunamis are one of the deadliest natural disasters ? Explain.

Ans. Tsunamis are no doubt one of the deadliest natural disasters. Their ill-effects are as follows :
1. Great Loss of Life. Tsunamis cause a great loss of life. A single tsunami of 26th December 2004 killed more than 2 lakh people and rendered many more homeless. Tsunamis not only do not spare those caught on the high seas but also take the people who are on the beaches in their wake. So much so, even the people living in the sea-shore colonies are caught – unawares in their sleep and killed.
2. Damaging Effect on Property. Such is the force of a tsunami that a wall of water, sometimes more than 30 metres high when rushes towards the land, spares nothing – houses, buildings, trees, all kinds of life – anything which comes in its path.
3. Great Damage to Port Cities. The different port cities, because of their location near the sea-shore, suffer the most as a result of tsunamis. Most of the ships are destroyed and the dockyards are damaged beyond repairs. Moreover, there is loss of bridges, streets, electric poles and different means of communications.
4. Rehabilitation Problem. The rehabilitation, apart from being a much painful process, entails unbelievable cost. As a result of the Tsunami which hit the Indian Ocean countries on 26th December, 2004, India alone had to bear a loss of about 10,000 crore rupees. Not only that, the Indian Government will have to spend a lot more on the rehabilitation of all those affected by this damaging tragedy.
5. A Great Loss to the Tourist Industry. Tsunamis leave behind many tragic memories, especially for places where tourists from foreign countries are caught in Tsunami waves and lose their lives. Naturally, tourists avoid visiting such places, which ultimately results in a great loss to tourism industry.


Q. 5. State any five measures during pre-tssunami scenario.

Ans. Some of the preparedness measures are the following which can prove useful before the Tsunami strikes :
1. You should know about distance of your house/school from the sea.
2. Know the elevation of the site of your house/school above mean sea level. Elevating your house will help you in reducing the damage to your property.
3. Ensure quality construction of your house.
4. Know the safe routes in case of evacuation.
5. Keep ready eatables like biscuits and chocolates, water, other supplies and things like a flash-light, a portable battery-operated radio, first aid kit, medicines, etc. in case of an emergency.


Q. 6. State any five measures during a tsunami scenario.

Ans. In case of tsunami does strike, the following measures should be taken.
1. Don’t be panicky, and if your house is in the low-lying areas, evacuate at it the earliest and shift to places situated at the higher levels.
2. Never go down to the sea-shore only to watch for a tsunami as it can be very dangerous.
3. As a tsunami is not a single wave but a series of waves, in case one wave is a small one, it can be followed by extremely large waves. So leave the sea-shore immediately and at the earliest.
4. When a tsunami warning is issued by the Pacific Tsunami Warning Centre, do pay respect to it. Don’t think that it is a false alarm. In May 1960, about 61 people were killed in Hawaii even after the warning because they thought it to be a false alarm.
5. Keep yourself well-informed through radio or television about the various emergency and relief activities being carried out.


Q. 7. Enlist the steps that need to be taken in post-tsunami scenario.

Ans. 1. In case you had to evacuated your house during Tsunami storm, go there at once and see what repair work needs to be done.
2. Try to rescue others in flooded areas and help the trapped as well as the injured persons.
3. You must stay out of those houses which are still under water due to tsunami storm, as they may collapse.
4. Beware of the wild animals, especially the snakes during relief operations.
5. Beware of the electric fittings that might have been damaged during the Tsunami attack.


Q. 8. Describe the Tsunami of 26th December, 2004 and why it is called the deadliest Tsunami ever.

Ans. The Indian Ocean Tsunami of December 26, 2004, generated by the most powerful earthquake in decades, proved to be perhaps the most destructive tsunami in history. More than 2 lakh people were killed and many more were rendered homeless.Severe earthquake of the magnitude of 9·0 on the Richter Scale caused this deadliest tsunami. Its epicentre was near the west coast of Sumatra, Indonesia. Within hours, the killer waves radiating from the epicentre rushed towards the coastline of 11 Indian Ocean countries, devastating everything that come in their way – killing people out at the sea, those present on the beaches and drowning even those sitting anawares in their homes ! Also, property worth thousands of crores of rupees was destroyed from Africa to Thailand. According to a preliminary estimate of the Government of India, the loss due to this giant tsunami could be over 5300 crore. Of all the states of India, Tamil Nadu suffered the most followed by Kerala, Andhra Pradesh and Pondicherry.