The beautiful seaside is always desirable, but the seaside is not always picturesque, sometimes, the sea will suddenly show a vicious side to humans, it will set off a huge wave of tens of meters in a short period of time, and then sweep everything on the seashore, this phenomenon is the "tsunami" we often hear.

If a 50-meter-high tsunami hits, is it better to plunge head-on into the water, or is it better to turn around and run inland?

The tsunami can actually be seen as an enhanced version of the wave, so we only need to briefly understand the operation mechanism of the wave to get the answer to this question.

If you look closely at the seabirds floating on the surface of the sea, you will find that they will follow the waves up and down, but in the horizontal direction, they will not show obvious displacement, as in the picture below.

Why is this happening? This is because the wave can be seen as a kind of horizontal wave, and the characteristic of the horizontal wave is that the direction of its particle vibration and the direction of the wave propagation are perpendicular to each other.

In the process of wave propagation, the trajectory of the various particles in the seawater is actually similar to that of seabirds floating on the surface of the sea, if we look at the various particles in the seawater, we will find that they only regularly do reciprocating circular motion in the equilibrium position (as shown in the following figure).

It can be seen that with the increase of water depth, the radius of circular movement of seawater quality points will become smaller and smaller, and when the water depth reaches a certain level, the seawater quality points will be relatively stationary, and we will call this near interface that is just in a relatively static state "wave base".

Generally speaking, the depth of the "wave base surface" is 1/2 of the length of the wave, and in the process of wave propagation, if the depth of the seawater is greater than or equal to this value, then the wave is a deep water wave, and its propagation speed can be described by the general mechanical wave velocity formula "speed = wavelength/period".

If the depth of the seawater is less than 1/2 of the length of the wave, the wave will become a shallow water wave, and unlike the deep water wave, the propagation speed of the shallow wave depends on the depth of the seawater, which can be described by the formula "v = √gd" (Note: g is the acceleration of gravity, d is the depth of the seawater, and "√" refers to "under the root sign").

Suppose there is a wave propagating from the deep water area to the coast, then its propagation process is like this: when it is a deep water wave, its propagation speed is basically unchanged, and because the closer to the coast, the shallower the seawater, so when the depth of the seawater is less than 1/2 of the wave length, the wave will become a shallow wave, after which, as the sea continues to shallow, the speed of the wave will become lower and lower.

Since the period of the wave is only related to the wave source, so during the propagation of shallow water waves, its period is constant, in this case, if the speed is reduced, then its wavelength will become shorter, at the same time, its amplitude will become larger, so we will see that the closer the wave is to the coast, the higher the wave height, we can call this process "shoaling compression".

Under normal circumstances, when the depth of the sea is less than or equal to the wave height of the waves, the waves will not be able to maintain a stable waveform because the amplitude is too large, in this case, the waves will break (break), forming a "breaking wave", for the general waves, it is the "wave" that we are familiar with.

In the process of propagation of shallow water waves, due to the lack of depth of seawater, seawater quality points can not do reciprocating circular motion, their trajectory is actually "flattened", the shallower the seawater, the more "flat", when it reaches a certain level, the seawater quality point can almost only do back and forth movement (as shown in the following figure).

Tsunami mainly generated mechanism is the displacement of huge volumes of water, large-scale earthquakes, volcanoes, glacier collapses, landslides and other natural phenomena can trigger tsunamis, as an enhanced version of the wave, the wavelength and speed of the tsunami far beyond the general wave, its wavelength can reach hundreds of kilometers, the speed can usually reach 700 to 800 kilometers per hour.

When tsunami waves propagate in deep water, their amplitude is usually less than 1 meter, that is, tsunami waves in deep water, their wave height is usually within 0.5 meters, which is why ships located in deep water areas are basically unaware of tsunami waves.

In the shallow water area near the coast, the tsunami wave will be transformed from a deep water wave to a shallow water wave, and because the speed of the tsunami wave is extremely fast, the amplitude of the tsunami wave will increase rapidly in the subsequent "shoal compression", and eventually form a "breaking wave" that can be as high as tens of meters.

Although the speed of the "wave" has been greatly reduced, it can still reach the order of tens of kilometers per hour, and it will rush to the coast like a huge wall of water, and then sweep everything on the seashore.

Based on the above introduction, it is clear that if a 50-meter-high tsunami hits, it is definitely not a wise choice to plunge head-on into the water.

If someone did, he would first be subjected to the huge impact of the tsunami, and after that, he would not be safe in the water, because he would be sucked deep into the bottom of the "breaking wave", and then follow the movement of the sea and be thrown high to the top of the "breaking wave" (almost 50 meters in height), and then fall down hard.

It is important to note that other objects swept away by the tsunami will also go through the same process, so this person may also constantly collide with other objects, and each collision can be fatal under the power of the tsunami.

In addition, tsunamis generally have several waves, and their cycles are usually from a few minutes to tens of minutes, which means that it is unlikely that the above process will be repeated before long. For humans, a tsunami can't withstand (whether it swims or not), let alone several waves.

So when we perceive a tsunami coming, the best option is to turn around and run inland (running to a high ground, of course), because when the tsunami comes ashore, its speed and energy will quickly decay, so as long as we run fast enough and far enough, we can get out of danger.

In fact, if you see a 50-meter-high tsunami and then run, it is most likely that you can't run away, after all, the speed of the tsunami is so fast, but fortunately, there are usually signs before the tsunami strikes.

For example, abnormal fluctuations in ocean tides (when the tide rises, there is a low tide, and vice versa), abnormal ups and downs in the distant sea (abnormal rise or fall in sea level), or a large amount of sea water on the seaside may be a sign of a tsunami, so when we perceive these situations, we should leave the sea as quickly as possible and move to the high inland terrain.

Another thing to say is that because many tsunamis are caused by earthquakes, and seismic waves travel much faster than tsunamis, there are usually tsunami warnings before tsunamis strike, and when we receive early warnings, we should stay away from the coast, of course, if we detect an earthquake at the seashore, we should also evacuate as soon as possible.

Well, today we will talk about this first, welcome to pay attention to us, we will see you next time.

(Some of the pictures in this article are from the Internet, if there is infringement, please contact the author to delete)