THE KILLER WAVE by:- sricharan,10th cbseTSUNAMI

WHAT IS TSUNAMITsunami waves do not resemble normalsea waves, because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly risingtide, and for this reason they are often referred to astidal waves. Tsunamis generally consist of a series of waves withperiodsranging from minutes to hours, arriving in a so-called "wave train".Wave heights of tens of meters can be generated by large events. Although the impact of tsunamis is limited to coastal areas, their destructive power can be enormous and they can affect entire ocean basins; the2004 Indian Ocean tsunamiwas among the deadliest natural disasters in human history with over 230,000 people killed in 14 countries bordering theIndian Ocean.

Generation mechanisms

The principal generation mechanism (or cause) of a tsunami is the displacement of a substantial volume of water or perturbation of the sea.This displacement of water is usually attributed to either earthquakes, landslides, volcanic eruptions, glacier melting's or more rarely by meteorites and nuclear tests.The waves formed in this way are then sustained by gravity.Tidesdo not play any part in the generation of tsunamis.

Tsunami due to Earthquakes When there are earthquakes in sea bed or when there is any sudden jerk in tectonic plates there is a rush of water up due to this action water waves generate speed up to 500 km/h .When this waves is nearer to the shores its speed suddenly decreases to 45km/h but the height of the waves go up to 10m high .This is the killer wave called tsunami. More the depth of the seas more destructive is tsunami .

DEVASTATION BY TSUNAMI

Tsunamis cause damage by two mechanisms: the smashing force of a wall of water travelling at high speed, and the destructive power of a large volume of water draining off the land and carrying a large amount of debris with it, even with waves that do not look large.The reason for the Japanese name "harbour wave" is that sometimes a village'sfishermenwould sail out, and encounter no unusual waves while out at sea fishing, and come back to land to find their village devastated by a huge wave.Not only the damages by wave on its way to the shore it brings large stones , boats , etc. This can take many life's and can injure 1000s of people.

Scales of intensity and magnitude of wavesAs with earthquakes, several attempts have been made to set up scales of tsunami intensity or magnitude to allow comparison between different events. One of the common scale is ricther scale it contain variation from 1 to 10 each division has different effect.

Tsunami proof house

Improving in technology has enabled man to build tsunami proof houses which can reduce damage created to ones property one of the most common houses are built as follows :-Coastal homes are elevatedThese are built in hydrodynamics structure which ensures easy flow of water and protect homes from collapsing .battery walls can be put .There must be deep protection to the foundation of the buildings.

Pictures of tsunami proof house

Detecting tsunamiOnly some machines have been introduced to detect tsunami which mainly depend on satellites and sonar to detect tsunami.

Many measures have been taken to reduce damage created by tsunami. Government has been giving education to the coastal people about the dos and don'ts during tsunami many boards have been put up to warn the people before entering tsunami prone area

Tsunami as a weaponScientists have been trying to use tsunami as a weapon over countries during wars by creating a destructive waves . This can be done by exploding nuclear weapons in sea bead which creates destructive waves . This was first tried by New Zealand Military Forces.

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