The document provides information about tsunamis presented by Harsh in standard VIII A. It defines tsunamis as a series of large ocean waves caused by earthquakes under the sea. The largest tsunami was in Lituya Bay, Alaska in 1958. Earthquakes are the main cause of tsunamis as the movement of tectonic plates under the sea can sometimes cause huge displacements of water. Proper warning systems and evacuation procedures help minimize loss of life from tsunamis.

1. TOPIC -TSUNAMI
PRESENTED BY - HARSH
ROLL NO - 08
STANDARD - VIII A

2. IMPORTANT FACTS ABOUT
TSUNAMI
.Tsunami is a Japanese word which means
‘harbour wave’
.Earthquake under the sea are the main
causes of tsunami
. The biggest Tsunami ever was at lituya bay
,alaska on 9 july,1958 .Earliest
tsunami was in sicily 8,000 years ago
. Landslides and volcanoes can also cause
tsunami

3. INTRODUCTION
A tsunami is a powerful series of waves
caused by a disturbance under water.
This is usually an earthquake under
the sea.
killed and buildings destroyed The
waves travel through the ocean and
cause devastation when they reach
land. Humans are often when the
water hits the coast.
. To fully understand how tsunamis
are caused we must have an
understanding oftectonic plates, earth
quakes, and finally, water

4. Panic :people flee as a tsunami wave
crashed into trees in Indonesia on
Boxing Day , December 26, 2004

5. What is tsunami.Tsunami is a Japanese word meaning 'harbour wave' that
refers to a series of large ocean waves that hit a shoreline.
The word originates from Japan because this is the country
where tsunamis are most common.
These tsunami waves may be as long as 100km and travel
across the ocean at speeds of up to 800kmh. There may be a
constant stream of waves that that batter the shore for
between 10 and 60 minutes.
Tsunamis are also known as tidal waves, due to their large
and powerful nature. They have been depicted throughout
history, art, television and film as something terrifying,
cataclysmic and almost Armageddon-like
.

6. IMAGES OF TSUNAMI

7. Can anything be done?
 Unfortunately nothing can be done to prevent Tsunamis. However, there are several
organisations that use complex technology to monitor movement of the earths plates and
sudden changes in water movement. There are also warning and evacuation procedures in
place around countries like Japan and Hawaii where Tsunamis are frequent.
Any sudden earthquake that happens underwater will be detected in the same manner of
on on-shore earthquake. These are measured in the Richter scale. If this is recorded then
warning systems can sometimes be activated to evacuate people.

8. Tsunami history
Indonesia - 26 December 2004
Papua New Guinea - 17 July 1998
Sea of Japan - 26 May 1983
Alaska British Columbia - 27 March 1964
Chili - 22 May 1960
Aleutian Islands - 1 April 1946

9. What causes a Tsunami?
1. Tsunamis are caused by sudden movements
of the earth that happens under the sea. Often
the most destructive Tsunamis are caused
by earthquakes but causes can also include
volcanic eruptions, landslides or even a comet
hitting the sea .
2. Landslides cause tsunamis when the debris
falls into the water. This has the same effect of
dropping a large stone into a pool - big ripples
are created. But when this happens in the sea
and it is thousands of tonnes of rock and earth
falling into the sea a very large ripple, more
like a tidal wave is created. This travels across
the sea until it comes into contact with land
and a tsunami is formed

10. What causes a Tsunami?
3. Volcanoes cause tsunamis when there is an eruption. The
volcano can either be on land or under the sea, in which
case it is known as a submarine volcano. If the volcanic
eruption happens on land, the tsunami is caused by debris
and lava from the volcano flowing into the sea, which once
again causes a bug ripple.
4. If the eruption happens under water, the enormous power
of the eruption sends shudders through the earth and
disrupts the water. The water in the sea then breaks into
waves which travel across the ocean until they come into
contact with a coast. Here, a tsunami is formed.

11. How tsunami works

12. How do undersea earthquakes start?
The most common cause of a tsunami is fro earthquakes. This is what caused the Boxing Day tsunami in the Indian
Ocean in 2004 and it is also the reason behind the 2011 Japan tsunami.
To understand how earthquakes cause tsunamis we must first fully understand what causes earthquakes. Remember,
tsunamis are an after-effect of an earthquake.
The earth sits on about a dozen tectonic plates. These are large floating peices of hard rock that are constantly moving
and fit together around the world like a jigsaw.
Undersea earthquakes happen when one of these plates is rubbing against another at a plate boundary. The two plates
may become stuck as the heavier plate tries to slide under the lighter other. This causes a build up of pressure in a process
knows as subduction.
As the heavier plate continues to slide beneath the lighter plate, it causes the lighter plate to bend downwards with the
pressure. A point comes when the lighter plate can no longer take the intense pressure and suddenly snaps back up to the
surface where it had been before.
The incredible force of the earth's plate shooting upwards in the water causes a huge rise in sea level. A vast body of water
moves upward - like a huge mountain of water in the sea.

13. Now read these other great information-packed tsunami hubs
 What are the effects of a tsunami?
The effects of a tsunami are devastating. They are only of the world's worst natural disasters that
can hit a country. Tsunami damage is first caused by the immense force of the tidal wave hitting
the...
 The biggest tsunamis in history
The biggest tsunami ever was caused y an enormous 8.3 magnitude earthquake in Alaska on July
9, 1958. A landslide of rock fell into a lake and caused a wave bigger than the Empire State
Building. Read more...
 What are tsunamis and where do they happen?
Tsunamis are large, powerful waves that hit land and have devastating effects. They most often
begin in the ocean and travel through the water to the nearest coastline.
 How to survive a tsunami: A guide to escaping a natural disaster
Millions of people have been killed by tsunamis in the last hundred years alone. But there are
precautions that everybody can take to saves lives and prevent injury.
 Japan 2011: The tsunami that caused a nuclear meltdown
The tsunami that hit Japan in March 2011 caused widespread devastation, but also threatened
one of the worst nuclear meltdowns that the world has seen in decades. Six months on, the country
is still struggling to contain radiation levels at the damage

14. Thank you
and
have a nice day
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