The document discusses tsunamis, including their causes, characteristics, and historical examples. It provides details on underwater earthquakes triggering tsunamis and describes tsunamis as consisting of multiple waves rather than a single wave. Examples of destructive tsunamis throughout history are given for various regions.

4. What is a tsunami?
• A tsunami is a series of
waves created when water
is moved very quickly.
Underwater earthquakes
are the most common
causes of tsunamis, but
underwater volcanic activity
can also trigger a
displacement in the water,
and create a mega-wave.

6. • First tsunami was recorded in 1480 B.C. in eastern
Mediterranean, when the Minoan civilization was waped
out.
• A large tsunami accompanied by the earthquake of
Lisbon in 1755.
• North and South American records have dated such
events back to 1788 for Alaska and 1562 for Chile. Records
of Hawaiian tsunami go back to 1821.
• Tsunami hits the Mona Passage off Puerto Rico in 1918,
grand banks of Canada in 1929.

7.  Hawaiian tsunami on 1 April 1946 destroyed the city of
Hilo, killing 159 people. Other recent tsunami that have
hit Hawaii are those of 1952,1957,1960,1964 and 1975 .
 Total 65 destructive tsunamis struck Japan between 684
A.D to 1960.
 On 16 August 1976, a large earthquake in the Moro Gulf
in the Philippines generated a destructive local tsunami
which killed over 8,000 persons.
 Last one was Christmas tsunami in 2004.

8. Tsunami "Wave Train"
Many people have the mistaken belief that
tsunamis are single waves. They are not.
Instead tsunamis are "wave trains" consisting
of multiple waves. The chart below is a tidal
gauge record from Onagawa, Japan beginning
at the time of the 1960 Chile earthquake. Time
is plotted along the horizontal axis and water
level is plotted on the vertical axis. Note the
normal rise and fall of the ocean surface,
caused by tides, during the early part of this
record. Then recorded are a few waves a little
larger than normal followed by several much
larger waves. In many tsunami events the
shoreline is pounded by repeated large waves.

10.  Volcanic eruptions
 Icefalls
 Heavy rainfall
 Seismic activities
 Submarine landslides
 Cosmic impacts

11. • Volcanic eruptions and icefalls create
disturbance in water and generate
tsunami.
• Heavy rainfall cause overflow of
water and generate tsunamis.

12. .Tsunami can be generated when the see
floor abruptly deforms and vertically
displaces the overlying water.
.Tectonic earthquakes are a particular
kind of earthquake that are associated
with the earth’s crustal deformation,
when these earthquakes occur
beneath the see, the water above the
deformed area is displayed from its
equilibrium position.
.Waves are formed as the displaced
water mass, which acts under the
influence of gravity, attempts to regain
its equilibrium

13. • Ocean waves are normally divided into 3
groups, characterized by depth:
• • Deep water
• • Intermediate water
• • Shallow water
• Even though a tsunami is generated in
deep water (around 4000 m below mean
sea level), tsunami waves are considered
shallow-water waves. As the tsunami
wave approaches the shallow waters of
shore, its time period remains the same,
but its wavelength decreases rapidly,
thus causing the water to pile up to form
tremendous crests, in an effect known as
"shoaling".

14. Subduction Zones are Potential Tsunami Locations
Most tsunamis are caused by earthquakes
generated in a seduction zone, an area where
an oceanic plate is being forced down into
the mantle by plate tectonic forces. The
friction between the sub ducting plate and the
overriding plate is enormous.
This friction prevents a slow and steady
rate of seduction and instead the two plates
become "stuck".

15. Accumulated Seismic Energy
As the stuck plate continues to descend into the
mantle
the motion causes a slow distortion of the
overriding plage.
The result is an accumulation of energy very similar
to the
energy stored in a compressed spring. Energy can
accumulate in the overriding plate over a long
period of
time - decades or even centuries.

16. Tsunamis occur most frequently in the Pacific
Ocean, but are
a global phenomenon; they are possible
wherever large bodies of
water are found, including inland lakes, where
they can be caused
by landslides.
Japan is a nation with the most recorded
tsunamis in the
world. The earliest recorded disaster being that
of the 684 A.D.

17. .Tsunami is one of the earth’s disaster. It was a Japanese
word
meaning “harbor wave,” used as the scientific term for a
class
of abnormal sea wave that can cause catastrophic
damage when it hits a coastline.
.Tsunamis can be generated by an undersea earthquake,
an undersea landslide, the eruption of an undersea volcano,
or by the force of an asteroid crashing into the ocean.

18.  The earthquake that caused the Sumatran tsunami
is the second largest to ever be recorded on a
seismograph.
 The magnitude of the earthquake was 9.3 on the
Richter scale.
 This earthquake had the longest duration, that is
lasted for the longest amount of time, ever
observed, lasting approximately 10 minutes.
 It caused the entire planet to vibrate by as much as
1 cm (0.5 inches), and triggered other earthquakes
as far away as Alaska.

19.  There were no Tsunami Warning Systems in the
Indian Ocean on the 26th December 2004. Had
there had been, many lives could have been
saved.
 A 10 year old tourist named Tilly Smith, who
had studied tsunamis at school, noticed the
receding tide and frothing bubbles, and told her
parents there was going to be a tsunami. Her
parents told the rest of the beach and everyone
was evacuated safely.

20. View of a Tsunami Taken By A Satellite

21. GENERATION OF TSUNAMIS
A Tsunami is generated when a large
amount of water is displaced which is
done-:
 Mainly By The Earthquakes.
 By The Landslides.
 By Volcanic Eruptions.
 By Impact Events like Meteorite impacts

22. Earthquakes – The Major Cause
 The Sea floor abruptly
deforms and displaces the
sea water lying above.
 Large vertical movements
of earth's crust can occur at
plate boundaries which are
called “faults”.

23.  Tsunamis may reach a maximum vertical
height onshore above sea level, often called
a run up height, of 10, 20, and even 30
meters.
 For a typical ocean Depth of 4000m, a
tsunami moves with a speed about
700km/hr.
 The fast-moving water associated with the
inundating tsunami can crush homes and
other coastal structures.

24. The Tsunami Affected Countries

25. The Tsunami Affected Countries

26. Signs Of An Approaching Tsunami
 Often no advance
warning of an
approaching Tsunami
 An earthquake felt near a
body of water may be
considered an indication
that a tsunami will shortly
follow.

27. WARNINGS AND PREVENTION
 Early warnings come
from the nearby animals
as they sense danger
and flee to higher
grounds.
 Tsunami walls for the
reduction in the damage.
 Tsunami warning system
alert the people before
the wave reaches the
shore

28.  Tsunami death toll
tops 118,000.
 Around 10,000 killed in
India.
 In Thailand, more than
4,000 are feared dead
and dozens of deaths
are reported in
Malaysia, Myanmar
and Maldives.
 WHO estimates five
million people are
without basic needs.

29. Calong, A land of 13,000 “ vaporized”
by Tsunami

30. The Tsunami
That Struck
Thailand
On
December 26, 2004

31. The Islamic Relief
 Responded to the emergency
in hours.
 Building enough homes to
accommodate five families a
week.
 Highly successful because of
the close and constant
involvement of the affected
communities.
 Still working for the
betterment of the victims.

32. RELIEF WORKS IN INDIA
 Donations done under
the Prime Minister Relief
Fund.
 Rice, mats, medicines
were provided.
 ITC distributed over 1
lakh shirts to the victims.
 New houses were
provided.

33.  Loss of life and property can be reduced by
proper planning.
 Tsunami warnings can be made to aware
peoples.
 Stay away from all low lying coastal areas.
 Never go down to the shore to watch
tsunami.
 Stay out of low lying danger areas until an
“all-clear” is issued by competent authority.