Over the past decade, the number of natural disasters in the world has more than doubled. The most dangerous natural phenomena include the tsunami - huge killer waves.
Do you think 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 us what to do in order not to suffer from the action of the killer wave.
Did not work out? Then read this article carefully, perhaps this information will someday help save your life.
What is a tsunami?
It will be about the tsunami - the modern society should know the causes and consequences of this phenomenon. A well-known term came to us from Japan, and it is not surprising because it is this country that most often suffers from killer waves. Japanese tsunami is indicated by two hieroglyphs: 津 - “bay, port, bay” and 波 - “wave”. Therefore, in direct translation, this word means "wave in the bay." These are huge waves originating in the depths of the ocean and with huge destructive force crashing ashore.
Damaging factors of the tsunami can be defined as primary and secondary. Primary include:
- shock of a wave;
- air wave preceding flooding;
- hydrodynamic pressure;
- secondary are:
- complete flooding of the terrain;
- throwing ships ashore;
- the destruction of buildings, roads, bridges, power lines and other objects that come in the way of the wave;
- death of all living things;
- soil erosion, the destruction of agricultural plantations;
- fires.
Where is the most common occurrence of this?
The causes of tsunamis are most often associated with geological activity. Most likely, this phenomenon can be found on the Pacific coast. This is due primarily to the high geoactivity of this basin. Over the past millennium, these territories have been hit by killer waves more than 1000 times. At the same time, this phenomenon was observed several times less in the Indian and Atlantic oceans.
In Russia, the most dangerous, in terms of the occurrence of the tsunami, the Kuril and Kamchatka coasts, as well as the island of Sakhalin.
Killer Wave Parameters
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, a tsunami has a length, height and speed of movement.
- The wavelength refers to the horizontal distance between two peaks (crests) of adjacent waves. The average killer wavelength can range from 150 to 300 km.
- The height is the distance between the crest and the sole of one wave. Above the center of tsunami occurrence, this indicator can be quite small - from 1 to 5 meters.
- Velocity is the linear velocity of a particular element, such as a crest. Most often, this figure ranges from 500 to 1000 km / h, which, you see, is very much.
All tsunami wave indicators depend on the depth of the place of occurrence. The deeper the wave arose, the greater its length and the higher the propagation speed, but the height will be just small. For example, the speed of tsunami propagation in the Pacific Ocean, whose average depth is about 4 km, is approximately 700-800 km / h. When approaching the coastline, the wave propagation velocity decreases sharply to 80–100 km / h. Thus, the smaller the depth, the shorter the waves, but the height when approaching the shore increases sharply. In some cases, it can reach 45-50 meters.
Intensity
Before we talk about what is causing the tsunami, we will consider the intensity parameters 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 very weakly expressed, such a tsunami can be registered only with special instruments - seaographers;
- 2 points - a rather weak wave, which can only flood a flat coast; mostly experts can also notice it;
- 3 points - a tsunami of medium power, anyone can notice it; it is characterized by flooding of the flat coast, light destruction of coastal buildings; light boats can also be thrown ashore;
- 4 points - a rather severe natural disaster; the coast is completely flooded, and all coastal structures have significant damage; light motor boats and rather large sailing boats were washed ashore and then washed back; the coastline is littered with sand, silt and debris; human casualties are also likely;
- 5 points - a very strong phenomenon, accompanied by many victims; the coastline is severely destroyed for many hundreds of meters, large vessels are thrown ashore; nearby rivers overflow from a strong storm surge of water;
- 6 points - catastrophic consequences; the land is completely flooded for many kilometers inland, there are massive casualties, there is a complete devastation of the surrounding territories.
Why are there killer waves?
So we come to the question of why these terrible waves arise. To begin, we list the causes of the tsunami briefly:
- landslides;
- earthquakes;
- volcanic eruptions;
- meteorite falls;
- human activities.
The main cause of the killer wave is an underwater earthquake with a sharp rise or fall in the level 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 focus is not too deep.
Landslides are another reason. They account for about 7–8% of the elements. This reason for the occurrence of storm waves and tsunamis is secondary, as landslides most often occur as a result of earthquakes.
The third reason is the underwater eruption of volcanoes. Strong submarine eruptions have about the same effect as earthquakes. The largest and most famous eruption happened in 1883. The volcano Krakatau caused the emergence of a huge tsunami that destroyed more than 5,000 ships, about 36,000 people died around the world.
The rapidly developing nuclear energy has formed the prerequisites for the emergence of another reason for the appearance of giant waves - human activity. Various deep-sea tests, such as atomic explosions, are also capable of causing a phenomenon such as tsunamis.
A very small, but still a percentage, is given to cosmic phenomena, for example, the fall of meteorites.
It is worth noting that giant waves are most often the result of not one, but a number of factors. And in this case they are especially destructive. These may be the main causes of the tsunami.
Effects
One of the worst consequences of the tsunami, of course, is human casualties. Even one life of a person buried by a wave is already a great sorrow. What can we say about the hundreds and thousands of dead.
In addition, tsunamis cause salinization and erosion of large sections 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 the tsunami?
The causes of the tsunami are more or less clear, but how to recognize signs that portend trouble?
The very first approach of natural disasters is usually felt by birds and animals, who begin to leave their homes. Massive "moving" of the beast can begin both a few hours and a few days before the disaster. Probably birds and animals feel some energy waves sent by mother earth. In fact, an electromagnetic field acts on animals: a whole stream of charged ions rises from the surface of the earth into the atmosphere, charging the air with electricity to the limit. By the way, not only animals feel such a phenomenon - many so-called weather-dependent people have an unbearably headache.
If you live on the coast, get yourself an aquarium and carefully watch its inhabitants. This is exactly what the Japanese are doing, which for many decades have determined the approach of seismic activity by the behavior of aquarium catfish. In anticipation of shocks, these fish behave very restlessly, trying to literally jump out of the aquarium.
Clear signs of a tsunami approach may look like this:
- water quickly and suddenly departs from the coast, leaving a wide strip of sand;
- there are signs of a small (or strong) earthquake, although this point is not necessary at all, since the epicenter of the earthquake can be far in the ocean, and not felt at all on the shore;
- the movement of the waves is accompanied by sounds like thunder;
- change in the behavior of animals, birds and fish (they can be washed ashore).
What should you do if you notice a wave approaching?
If you notice such causes of a tsunami as an earthquake or a meteorite fall or you see obvious signs of its approach, do not hesitate to wait a second. Take along the most valuable things and documents, take children and elderly relatives, and as soon as possible leave the coast deep into the mainland. Make a reservation in advance with your family in case you lose each other.
If there is no way to quickly leave a dangerous place, look for other ways to save. It may be some kind of natural hill - a mountain or a hillock. Also suitable are high capital buildings made of stone or concrete. Best of all, if they will still be at least a little further from the coast.
You need to move the shortest way, avoiding the banks of rivers and various water bodies - bridges, dams, reservoirs. Safe can be considered a distance of at least 3-5 km from the coastline.
Try to stay calm - panic only interferes. The occurrence of a tsunami is usually recorded by devices and the warning system is turned on . Never ignore these sounds, even if several times it turns out that the alarm is false.
Never stay to look at the tsunami and do not approach the shore for 3-4 hours after the arrival of the first wave. The fact is that the wave is rarely one - the second, or 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 truly save your life. Follow them whenever you notice the first signs of an approaching killer wave. Do not ignore the sounds of the siren even if everyone around you says that the alarm is false.
Conclusion
Now you know exactly the causes of the tsunami and their possible consequences. I would like this knowledge to really help in a difficult situation. Remember, a tsunami is a very fast and extremely dangerous natural disaster. Knowing the causes of this phenomenon and the elementary rules of behavior can really save your life.