The tsunami in translation from Japanese is meant by a "huge wave". And in fact this name completely justifies itself. Scientists put forward the various reasons of formation of a tsunami, but the main is an underwater earthquake.
Mechanics of education
Owing to a tremor at an ocean floor shifts as one part of a bottom begins to tower begin to happen, and other falls. All this leads to the movement of the water reaching a surface when all this weight tries to return to an initial state there is a formation of huge waves.
If tremors occur in the open ocean, height of the waves which are given rise there very seldom exceeds an indicator in 1 meter, it is considered that deep oceanic earthquakes are not terrible for navigation as waves have big width between crests.
When earth movement happens closer to the coast, the speed of a wave falls, and its height, on the contrary, increases and can sometimes grow to 30 or 40 meters. These massive thicknesses of water also fall upon the coast, and they are called by tsunami.
Wave birth reasons
As it was already told above, the underwater earthquake is one of the most common causes of formation of huge waves. About 85% of all tsunami fall to its share, but scientists say that not all tremors in the ocean provoke the birth of high waves. So, about 7% of huge waves are formed owing to landslides. For example, it is possible to give the case taking place on Alaska: there was a landslide which from height of 1100 meters got to water and by that provoked emergence of a tsunami with a wave more than 500 meters. Of course, such cases very rare, happen landslides under water in deltas of the rivers more often, and they do not bear danger. One more of the reasons of formation of a tsunami is a volcanic eruption, falls to its share up to 4.99% of a tsunami. Such eruption under water to similarly usual earthquake. However the mechanism and consequences of the movement of bark are essentially various. If there is a strong volcanic eruption, from it not only tsunami are formed, in the course of eruption the rock cavity cleaned by a lava is filled with water, after eruption the underwater hollow or the so-called underwater lake is formed. As a result of eruption very long wave is born. The example of rather recent birth of such wave mode is a volcanic eruption of Krakatau. Meteorites can become the reason of formation of a tsunami, falling to the ocean is more right than them, but such cases are very rare. In each of the listed above cases there is a formation of a tsunami practically according to the similar scheme: water moves vertically, and then is returned to a starting position.