Tsunami - a huge ocean waves that are formed because of the powerful impact of natural disasters in the entire water column.
On the shores of the Pacific Ocean there is more than 80% of cases, the appearance of a tsunami.
The main cause of tsunamis areunderground earthquake. They account for over 85% of cases of these huge waves. When an earthquake on the ocean floor there is a vertical ground motions. Part of the bottom rises, and the other - is omitted. ocean surface begins to oscillate vertically in an effort to return to its original position, and that gives rise to a series of long waves.
Not every underwater earthquake leads tothe formation of a tsunami. Progress of all the water reservoir can only carry a fairly strong earthquake with a hearth located deep under the bottom. In addition, underwater tremors should enter into resonance with the vibrations of the waves.
About 7% of the tsunami are the result of landslides. earthquake often leads to landslides, and it has already generated a powerful wave. Due to the earthquake in Alaska in 1958 Lutuyya bay landslide occurred. A huge mass of ice and rock collapsed from a height of 1,100 meters in water. There was a wave that reached a height of over 520 meters on the opposite shore of the bay.
In the underwater volcanic eruption fallsabout 5% of a tsunami. Strong volcanic explosions cause the shock wave shakes the water mass. In addition, water is set in motion in an effort to fill the voids of erupted material. Huge tsunami spawned the eruption of Krakatoa in 1883.
The cause of the tsunami could be, and human activity. In 1948, as a result of underwater atomic explosion produced by the United States, there was a wave height of 28.6 m.
The fall of a large meteorite in the ocean can also trigger devastating waves.
Waves up to 21 meters in height can be formed due to thehurricane force winds. However, they are not tsunami, since in this case no shifts the whole thickness of the aqueous layer. In addition, wind waves are short and can not cause significant flooding on the coast.