Tsunami

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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.

TSUNAMI IS A JAPANESE WORD MEANING ‘HARBOR WAVE’. IT IS CONSTITUTED WITH TWO SYLLABLES, JAPANESE LANGUAGE MEANING HARBOUR ("TSU", 津 ) AND WAVE ("NAMI", 波 ).

TSUNAMI IS A WAVE TRAIN OR SERIES OF WAVES GENERATED, BY IMPULSIVE DISTURBANCE THAT VERTICALLY DISPLACES THE WATER COLUMN, IN WATER BODY. EARTHQUAKE, LANDSLIDES, VOLCANIC ERUPTION, EXPLOSION AND EVEN THE IMPACT OF COSMIC BODIES LIKE METEORITES COMMONLY GENERATE TSUNAMI. TSUNAMI SAVAGELY ATTACKS COASTLINES CAUSING DEVASTATING PROPERTY DAMAGE AND LOSS OF LIVES.

• 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.

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.

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.

Volcanic eruptionsIcefallsHeavy rainfallSeismic activities Submarine landslidesCosmic impacts

• Volcanic eruptions and icefalls create disturbance in water and generate tsunami.

• Heavy rainfall cause overflow of water and generate tsunamis.

.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

• 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".

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".

Subduction Zones are Potential Tsunami Locations

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.

Accumulated Seismic Energy

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.

.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.

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.

FACT!

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.

View of a Tsunami Taken By A Satellite

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

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”.

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.

Why It’s Destructive?

The Tsunami Affected Countries

The Tsunami Affected Countries

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.

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

The Destruction Of Tsunami

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.

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

On

December 26, 2004

The Tsunami That Struck

Thailand

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.

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.

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.

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