Causes of tsunami: signs of occurrence and danger of tsunami

Over the past decade, the number of natural disasters on the globe has more than doubled. The most dangerous natural phenomena include the tsunami - huge killer waves.

Do you think that you know enough about this? Then try to answer these simple questions:

• What are the causes of the tsunami?
• List the signs by which you can determine its approximation;
• Tell me what to do in order not to suffer from the action of the killer wave.

Did not work out? Then carefully read this article, perhaps this information will someday help save your life.

What is a tsunami?

It's about tsunamis - the causes of the onset and consequences of this phenomenon should be known to modern society. A famous term came to us from Japan, and it is not surprising that this country suffers most often from the waves of murderers. Tsunami in Japanese is denoted by two hieroglyphs: 津 - "bay, port, bay" and 波 - "wave". Therefore, in a direct translation, this word means "wave in the bay". These are huge waves that are nascent in the depths of the ocean and with a huge destructive force falling on the shore.

The damaging tsunami factors can be defined as primary and secondary. The primary are:

• Shock wave;
• Air wave preceding flooding;
• Hydrodynamic pressure;
• Secondary are:
• Complete flooding of the area;
• The release of ships ashore;
• Destruction of buildings, roads, bridges, power lines and other objects that fall on the way of the wave;
• The death of all living things;
• Soil erosion, loss of agricultural plantations;
• Fires.

Where is the most common occurrence of this phenomenon?

The causes of the tsunami are most often associated with geological activity. Most likely, this phenomenon can be found on the coast of the Pacific Ocean. This is primarily due to the high geo-activity of this basin. Over the last millennium, these areas have been hit more than 1000 times by assassin waves. At the same time, this phenomenon was observed several times in the Indian and Atlantic Oceans.

On the territory of Russia, the most dangerous, from the point of view of the tsunami, the coasts of the Kuriles and Kamchatka, and also the island of Sakhalin.

Parameters of the killer wave

Considering the causes of the tsunami, it is worthwhile first of all to talk about what parameters characterize such waves, how they can be measured. Like any other wave, the tsunami has a length, height and speed of movement.

1. The wavelength is the horizontal distance between two peaks (crests) of adjacent waves. The average wavelength of the killer can range from 150 to 300 km.
2. The height is the distance between the crest and the sole of one wave. Over the center of the tsunami, this indicator can be quite small - from 1 to 5 meters.
3. Speed is the linear speed of movement of a particular element, for example, a comb. Most often this figure ranges from 500 to 1000 km / h, which, you must agree, is very high.

All indicators of the tsunami wave depend on the depth of the place of origin. The deeper the wave was born, the longer its length and the higher the speed of propagation, but the height will be just a little. For example, the speed of the tsunami in the Pacific, whose average depth is about 4 km, is approximately 700-800 km / h. When approaching the shoreline, the wave propagation velocity sharply decreases to 80-100 km / h. Thus, the smaller the depth, the shorter the wave, but the height at the approach to the shore increases sharply. In some cases, it can reach 45-50 meters.

Intensity

Before talking about what is the cause of the tsunami, let us consider the parameters of the intensity of this phenomenon. Yes, the tsunami, like the earthquake, has a division, expressed in points. There are six levels in total and they mean the following:

• 1 point - the phenomenon is expressed very weakly, such a tsunami can be registered only by special instruments - seaographers;
• 2 points - a rather weak wave, which can flood only the flat coast; It can also be noticed mainly by specialists;
• 3 points - tsunami of average power, anyone can notice it; It is characterized by the flooding of the flat coast, light disruption of coastal structures; Also, light boats can be thrown ashore;
• 4 points - quite a strong natural disaster; The coast is completely flooded, and all coastal structures have significant destruction; On the shore, light motor vessels and rather large sailboats were thrown out, and then washed away; The coastline is littered with sand, mud and debris; Human victims are also likely;
• 5 points - very strong phenomenon, accompanied by numerous victims; The coastline has been severely damaged by many hundreds of meters, large ships have been thrown ashore; The nearby rivers emerge from the shore from a strong storm surge of water;
• 6 points - catastrophic consequences; The land is completely flooded for many kilometers inland, there are massive human casualties, complete devastation of the surrounding territories is observed.

Why do you get suicidal waves?

So we came to the question of why these terrible waves are arising. First, let's list the causes of the tsunami short:

• Landslides;
• Earthquakes;
• Volcanic eruptions;
• Falling meteorites;
• Human activity.

The main reason for the emergence of a wave-killer is an underwater earthquake with a sharp rise or fall of the seabed. About 85% of all tsunamis occur precisely for this reason. But not every underwater earthquake is accompanied by the appearance of a huge wave. Most often this happens when the hearth is not too deep.

Landslides are another cause. They account for about 7-8% of the bustle of the elements. This cause of the emergence of storm waves and tsunamis is secondary, as landslides are most often caused by earthquakes.

The third reason is the underwater eruption of volcanoes. Strong underwater eruptions have about the same effect as earthquakes. The largest and most famous eruption occurred in 1883. The Krakatoa volcano caused a huge tsunami, destroying more than 5,000 ships, around 36,000 people died around the world.

Rapidly developing nuclear energy has formed the prerequisites for the emergence of yet another reason for the appearance of giant waves - human activity. Various deep-water tests, for example, atomic explosions, are also capable of causing a phenomenon such as a tsunami.

Very small, but still percentage, given to cosmic phenomena, for example, the fall of meteorites.

It is worth noting that giant waves are often the result of not one, but a number of factors. And in this case they are especially destructive. These are the main reasons for the tsunami.

Effects

One of the most terrible consequences of the tsunami, of course, are human casualties. Even one life buried by a wave of man - already a huge grief. What can we say about hundreds and thousands of dead.

In addition, tsunamis cause salinization and blurring of large parts of the coast, as well as complete flooding of coastal areas. All ships moored offshore are destroyed, and nearby buildings and structures can be destroyed to the ground.

How to recognize the approach of a tsunami?

The causes of the tsunami are more or less clear, but how to recognize the signs that foreshadow trouble?

The very first approach of natural disasters is usually felt by birds and animals that begin to leave their homes. Mass "moving" of the beast can begin as in a few hours, and a few days before the disaster. Probably, birds and animals feel some energy waves sent by mother earth. In fact, the animals are affected by an electromagnetic field: from the ground to the atmosphere, an entire stream of charged ions rises to the limit, charging the air with electricity. By the way, this phenomenon is felt not only by animals - many so-called meteozavisimyh people begin to feel unbearably headache.

If you live on the coast, get an aquarium and carefully observe its inhabitants. This is how the Japanese act, who have for many decades determined the approach of seismic activity on the behavior of aquarium soms. On the eve of the tremors, these fish behave very restlessly, trying literally to jump out of the aquarium.

Explicit signs of approaching the tsunami may look like this:

• Water quickly and suddenly departs from the shore, leaving a wide strip of sand;
• There are signs of a small (or strong) earthquake, although this point is not at all necessary, since the epicenter of the earthquake can be far in the ocean, and on the shore it can not be felt at all;
• The movement of the waves is accompanied by sounds resembling thunder;
• The behavior of animals, birds and fish (they can be thrown ashore).

What should you do if you notice the approach of the wave?

If you notice such causes of tsunami, such as an earthquake or a meteorite fall or you saw obvious signs of its approach, do not hesitate for a second. Take with you the most valuable things and documents, take children and elderly relatives and as soon as possible leave the coast deep into the mainland. In advance, talk to your relatives about the place in case you lose each other.

If there is no way to quickly leave a dangerous place, look for other ways for salvation. It can be some kind of natural elevation - a mountain or a hillock. Also suitable are high capital buildings made of stone or concrete. Best of all, if they are still at least a little further from the shore.

You need to move the shortest way, avoiding the banks of rivers and various water objects - bridges, dams, reservoirs. A distance of at least 3-5 km from the shoreline can be considered safe.

Try to stay calm - panic only hinders. The appearance of a tsunami usually fixes the instruments and the warning system is activated . Never ignore these sounds, even if several times it turns out that the alarm is false.

Never stay to see the tsunami and do not approach the shore within 3-4 hours after the arrival of the first wave. The fact is that the wave is rarely one - the second, and even the third can come in 30 minutes or even after 3 hours. Before you return, make sure that everything is over.

Knowing these simple rules can really save your life. Follow them whenever you notice the first signs of the approach of the killer wave. Do not ignore the sounds of the siren, even if everyone around them assures that the alarm is false.

Conclusion

Now you know exactly the causes of the tsunami and their possible consequences. I would like that this knowledge really helped in a difficult situation. Remember, tsunamis are a very fast and extremely dangerous natural disaster. Knowing the causes of this phenomenon and elementary rules of behavior can really save your life.