Many people have heard the word “tsunami” more than once, but not everyone knows what it really is. From Japanese it is literally translated as “harbor” (“tsu”) and “wave” (“by us”).
This manifestation of nature makes us once again think about its majesty and freeze before its incomparable power.
Tsunami hazard
The danger that a tsunami carries with it has several factors at once. For starters, this is a remarkable force of destruction that moves with water. Compared to this power, man is just a small straw. Secondly, it is very difficult, almost impossible to predict the time of the tsunami and the specific location. Thirdly, it is impossible to see the thickness of the water that moves towards the coast from either the air or the ship. The fact is that the wave that will bring the tsunami ashore does not visually differ from any other. Its peculiarity lurks below, in the water itself. It captures with it not only the upper surface of the liquid, but “scoops” it from the very bottom.
In the end, from the place of "birth" of the tsunami wave to its deadly arrival may lie distances of several thousand kilometers. That is, the wave travels all this distance in the water column, and, as you know, under such circumstances it is not very loyal to all the objects that stand in its way. Due to the lack of resistance on the way, it saves and accumulates an enormous supply of energy, which then falls on land and people.
How and why do tsunamis occur?
However, what gives rise to these deadly waves? Some are mistaken in claiming that the tsunami originates in seismically dangerous zones. This reason is far from the only one. For example, volcanic eruptions at the bottom of the ocean, landslides (they can have starting points below sea level) also lead to the release of a huge amount of energy that must be released somewhere. First, the lower layers of water are displaced, causing very strong vibrations that cause the entire thickness of the water to move from its place and move to the shore, carrying enormous energy reserves.
Some put the tsunami next to the phenomena of the ebb and flow, but this is fundamentally wrong. It is known that ebbs and flows occur due to the forces of gravity of the Earth and the moon’s satellite, their interaction with the Sun - read more in our article: what causes the ebb and flow. As for the tsunami, the attractive forces of celestial bodies do not affect him at all.
Interestingly, in some cases the speed of the wave reached a huge value of 950 kilometers per hour! Calculating the speed of a particular water stream is very simple. It is necessary to take the magnitude of the acceleration of gravity (about 9.8 m / s), multiply by the depth, from where the wave begins (in meters), and extract the square root from this value.
As you approach the shore, the tsunami begins to slow down, as the depth decreases. If before all the mass of water moved in the "native", aquatic environment, then here it has to come into contact with the shore, which reduces the speed of the wave. When the depth becomes insufficient to fit all the moving water, the wave begins to surface.
Before the people who were ashore at the time of the approach of the tsunami, a really terrible picture appears: a huge wall of water, which moves to the land at a crazy speed. The water does not have time to stop completely, so it crashes ashore and destroys everything that gets in its way. The greatest peculiarity of such phenomena is where the bottom very smoothly reduces its depth. To date, services have been developed whose purpose is to warn of the approach of such water flows.
