Tsunamis

Physics of Tsunamis

A tsunami is defined as a series of waves of extremely long wave length and long period generated in a body of water by an impulsive disturbance that displaces the water ( What is a Tsunami Tsunamis are often connected to earthquakes in coastal or oceanic regions . Volcanic eruptions landslides nuclear explosions and impacts of asteroids , meteorites and comets may also be responsible for the generation of tsunamis ( What is a Tsunami

Tsunamis are recognized as shallow water waves ( Math of Tsunamis . A shallow water wave is formed when

the ratio between its wavelength and the water depth becomes very small . These waves can move at a speed that is equivalent to the square root of the product of the water depth and the acceleration of gravity , that is , 9 .8 m /s /s ( Waves of Tsunamis . Whereas waves that are generated by the wind may each have a period of five to twenty seconds and wavelengths varying from one hundred to two hundred meters a tsunami or shallow water wave may have a period from ten minutes up to two hours and a wavelength of three hundred miles or more ( Math of Tsunamis . The speed of a tsunami may be calculated as follows

Let S Speed

Let g acceleration of gravity (32ft /sec /sec , 9 .8m /sec /sec

Let d depth of water

S (g d )^ (1 /2

Source : Math of Tsunamis

Physics of Tsunamis 2

The rate of depreciation of the energy of a wave is reciprocally related to the length of the wave . This mathematical understanding leads to the following conclusions (1 ) The larger the length of the wave , the less is the loss of energy experienced by the wave and (2 ) The deeper the water , the higher is the speed and greater the distance that is traveled with energy loss that is limited in nature ( Math of Tsunamis . The example that follows helps to elucidate these concepts further

If the ocean is 20 ,000 feet deep (6100 m

S [ (9 .8m /s /s (6100m )]^ (1 /2

S 244 .5 m /s

The tsunami will travel at 244 .5 meters per second or at about 550 miles per hour (890

km /h ) equal to the speed of a jet airplane ( Math of Tsunamis

Wave energy is one determinant of the damage caused by a tsunami . But when the wave hits shallow water ' other factors may come into play to determine the damaging effects of a tsunami ( Waves of Tsunamis These factors may include the period of the wave and its velocity . The latter is calculated as the product of the frequency and the distance between two crests of the wave ( Waves of Tsunamis ' As the tsunami approaches land , it grows in height . With decreases in the depth of water , the velocity and length of the wave also decrease However , the energy of the wave remains almost constant ( Waves of Tsunamis

Physics of Tsunamis 3

The tsunami waves that devastated a number of...