Information about the tsunami

on earth, the power of the sea is the most elusive of all natural forces. The undercurrents and waves under the sea floor can sweep the whole ocean and devour the whole city, and they will leave tens of thousands of bodies. Looking back at history, the tsunami caused many sensational disasters. In almost all oceans, it is called fierce and overbearing, never invincible, never merciless, and the wave killer has attacked human beings again and again. The waves themselves are deadly and mysterious. They can reach 7 kilometers per hour, and an attack will cause the whole earth to shake. From the movie The Day After Tomorrow, we saw that the monstrous waves almost drowned the Statue of Liberty, and an avalanche of seawater flooded into the busy streets of new york. This ferocious monster is the most ferocious killer on earth-the tsunami. However, while we were still intoxicated with the visual stimulation brought by high technology, the real tsunami hit many countries along the Indian Ocean coast, killing more than 16, people. What made the tsunami so rampant?

on the morning of Sunday, December 26th, 24, the crustal movement under the Indian Ocean in the southwest of Sumatra Island, Indonesia suddenly changed, forming the third largest earthquake and tsunami in the history of the earth. This huge earthquake, in a few seconds, suddenly appeared a crater at the bottom of the ocean, which was 1 kilometers wide, thousands of kilometers long and several meters deep. The resulting violent sea water shock is equivalent to the energy of 1 million atomic bombs dropped on Hiroshima, Japan. In an instant, people and everything on the shore disappeared into the huge waves. The tsunami was caused by an undersea earthquake, and the underground fault was a reverse fault with a magnitude of 9.

The Indian Ocean tsunami triggered by a strong earthquake started to cause a human tragedy within a few minutes, and an hour or two later, it spread to 12 countries along the Indian Ocean coast, devouring the lives of 16, innocent people, resulting in a catastrophe. While we feel sorry for the victims, we also bless the survivors of the disaster. No matter rich or poor, no matter celebrities or ordinary people, when they face this huge wave, their life and death experiences give us enlightenment: first, people from different countries face the same natural disaster at the same time and place; Second, the fragility and tenacity of life.

What should we do when we encounter a tsunami?

First, an earthquake is the most obvious precursor of a tsunami. If you feel strong vibration, don't go near the sea and the estuary of rivers. If you hear a report about an earthquake nearby, you should be prepared for tsunami prevention and pay attention to TV and radio news. Remember, tsunamis sometimes reach thousands of kilometers away from the source a few hours after the earthquake.

Second, ships at sea should avoid returning to the harbor after hearing the tsunami warning. The gap and turbulence caused by the tsunami in the harbor are very dangerous. If there is enough time, the ship owner should drive the ship to the open sea before the tsunami comes. If there is no time to sail out of the harbor, everyone should evacuate the ships anchored in the harbor.

Third, when a tsunami lands, the sea water often rises or falls obviously. If you see that the sea surface is retreating at an unusually fast speed, you should immediately evacuate to the inland higher ground.

The earth is our living home given by the universe, but it sometimes changes its face. The sea is the source of life given to us by the earth, but it also gets angry sometimes. Looking back at yesterday's disaster, I found the true feelings of the world; Remember the lesson of blood and cherish today's peace. Let's join hands to live in harmony with the earth and the sea.

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You may also know that there was an American blockbuster "The Day After Tomorrow" broadcast nationwide last year. I don't know if you have seen it. The plot of this film is like this. It talks about three kinds of disasters, one is a tornado, the other is a tsunami, and the other is low temperature and cold. The reason for these disasters is the greenhouse effect, because people use too much energy and cars smoke too much, and various influences make the whole. Originally, the earth has achieved a balance after 4.6 billion years. Due to the greenhouse effect, climate warming caused the melting of polar ice sheets, resulting in the rise of sea level, so that the climate deteriorated extremely, causing disasters all over the world. In that film, the tornado hit Los Angeles, the tsunami hit new york, and the low temperature and cold threatened the vast areas of North America, where people lived and mankind fell into unprecedented disasters.

This clip is devoted to the tsunami. As you can see, in a high-rise place in new york, people are living leisurely, or working, or going to school. Suddenly, there is a strong wind, and the whole wave comes in and rushes into the city. People tell each other, help each other, and the waves behind them chase after them. Some people run forward, and some people fall down. There is a large library, which can avoid danger and take refuge. Some old people, with the help of their families, and some employees of companies, ran to the library together. When these people crowded into the library, the waves came from behind, and a person behind just went in and closed the door. The waves rushed to the door, and it was a scene at that time. The film you watched just now is not reality. It is an irresistible horror scene created by high technology. The director made the audience tremble. Although it didn't say today or tomorrow, it was deliberately put on the day after tomorrow. The title was called The Day After Tomorrow. However, after watching it, this result was achieved. People were worried about the future. Speaking of The Day After Tomorrow, there was a translation of the title. The original text is The

day after

tomorrow. As you can see, the translated name of Hong Kong, Macao and Taiwan is After Tomorrow, and it will be a long time. The translated name of our mainland is The Day After Tomorrow, which specifically refers to this day. In other Chinese-speaking areas, it is translated as The Doomsday, and the day after tomorrow. Isn't that the future? It's a disaster. It's a catastrophe. Why did I put the three translated names on this point? This shows that our understanding of the film is still not profound. The disaster is not a one-day or two-day problem, but a long one. Therefore, we should not treat the disasters on the earth lightly and must always pay attention to them. After watching this, we can say that the day after tomorrow, which we don't want, has finally arrived.

This Indian Ocean tsunami was caused by an undersea earthquake. Now we always talk about tsunami tsunami. Don't forget who recruited it. After the tsunami, I will say that not only earthquakes, but also huge tsunamis are mainly earthquakes, and most of these tsunamis provide energy for disasters, which is the undersea earthquake. Let's talk about a 9-magnitude undersea earthquake near Sumatra Island, Indonesia, since the earthquake records began. The third great earthquake of magnitude 9 and above, huge earthquake, because there are three earthquakes with the same magnitude, so let's rank it according to size. As you can see, it is the fourth. The Kamchatka earthquake in 1952 was 9.2 in the northern part of the Pacific Rim, 9.2 in Alaska in 1957 and 9.5 in Chile in 196. This is the leader, and Alaska in 1964 was 9.2. By the way, the magnitude we usually read in newspapers is generally called Richter scale, but it is called richter in the newspaper. It is a scale of magnitude, just like we say the temperature is Celsius, how much is Celsius and how much is Fahrenheit. We measure the temperature. Generally, we use a mercury thermometer, but we can also use a thermocouple, which belongs to a technical system. No matter what we use, its scale is fixed. What is zero degrees Celsius? Water freezes, which is doomed, so there is also a rule on the Richter scale. What is a zero-magnitude earthquake? It was Americans who first used a fixed instrument called Wood in Southern California? Anderson Seismograph, using this instrument, observed a millimeter amplitude at a distance of 1 kilometers, so its corresponding magnitude is called zero degrees Celsius, which is so decided. So in the future, when you look at the Richter scale mentioned above, you know that this will do. Therefore, Indonesia's strong earthquake of magnitude 9 ranked third in a hundred years, but the death of this earthquake and tsunami ranked first. I don't have all the data yet, so I will pick a part, 1755. There are 3, to 7, people, 27, people in Japan in 1896 and Messina in 198. This is not Mexico, but another place name, 85, people, 9 people in Chile in 196 and 15 people in Alaska in 1964. You think the whole number is declining, but suddenly Indonesia also went to the Indian Ocean this time in 24, and more than 16, people died in an earthquake and tsunami. The number of deaths is equivalent to the sum of the tsunami deaths in the Pacific coast for more than 1,3 years, because according to the statistics of 1,7 years, there were 26 devastating earthquakes and tsunamis around the world, and according to the records of the tsunami in the Pacific coast for more than 1,3 years, how many people died? 14, to 2, people died in the tsunami disaster. You see that our 16, people are not equivalent to it, which is an important reason why this disaster has attracted global attention. There are too many dead people.

Let's look at the formation of earthquakes. We know that any earthquake must be related to faults. My teacher, Professor Fu Chengyi, has passed away. Before his death, he once said a famous saying, "Where there is an earthquake, there must be faults." If you look for it, there must be faults. Conversely, in the second sentence, he said, "If there is a fault, there may not be an earthquake." You understand that there is an earthquake because there must be a fault. It depends on whether this fault is active or not. If we use an image, it is a dead fault or an active fault. At present, many big cities in Beijing and Tianjin are conducting an important part of earthquake work, called active fault investigation and seismic safety evaluation, to see where there is a fault under our feet. If there is, don't build this point in your building and your stadium, so we also participated in the construction of this Olympic venue, called active fault detection. So what is the fault type of this earthquake? So it is inevitable to talk about three types. There is a crack in the middle on the left and right of the fault, so if this fault is not like cutting tofu up and down, it is likely to come sideways and cut a knife obliquely. Then I am on the top and this is on the bottom, which is called hanging plate and footwall. If I do this, I will slide down according to my own momentum, which is called normal fault. However, if I am pushed up by external force, it is called reverse fault. For example, I don't move like this, you know, it's called a horizontal inference layer and a translational fault. If such a movement occurs, its earthquake won't cause a tsunami, because it won't lift or pull down the water body above, but I am inclined a little bit, and there is a dip-slip component. When the dip-slip component is pushed up, hundreds of millions of tons of water on it are pushed up. The power of this earthquake is very, very great, and the energy of more than 1, kilometers of faults is released at once in this place. Here, by the way, I will give you a concept of what is the energy of plate movement. As we all know, the global plate movement is squeezing each other. This energy is very large, so the energy of earthquake is a part of the energy of plate movement, a very small part, so the earthquake that comes out now causes tsunami and wave fluctuation, so it is also a part of its earthquake energy. Then, who provides the energy of plate movement is the mantle below the earth. There is convection inside, and the earth's core is under the mantle, which is hot, just like we bake pancakes at home. No one expected that there is coal under this crust. The center of the whole earth is boiling hot, with a temperature of several thousand degrees and millions of atmospheres. It is baking our earth and constantly releasing energy, but we didn't study it enough in the past. In 1997, Song Xiaodong, a scientist in China, discovered it. This was unknown in the past, and it was thought that they were closely connected with each other, just like the egg skin was attached to the egg white and the egg yolk was attached to it. No, now the egg yolk is turning inside, and it is still very fast. This is a great contribution of China people, and a young man went there to study. That is to say, the energy of the whole earth is affecting people from bottom to top, providing people with living conditions and bringing disasters at the same time.

To put it simply, there are three indispensable conditions for the formation of earthquake and tsunami disasters. The first is that the depth of the deep sea is several hundred kilometers, the second is that the magnitude of the earthquake is above 7.5, and the third is favorable coastal and seabed geographical conditions, that is, topography. When our tsunami reaches the coastline and lands, if it enters the harbor or harbor, why is it dangerous in this place? Because there is also so much water coming, now it is not an open space, but a very narrow road. The water has to go from here, but it can't pass. You squeeze me, I squeeze you, and it will squeeze up. It will squeeze up a very high water column, which is easy to understand. Then let's say that not all undersea earthquakes will cause tsunamis. Some people have done statistics. Of the 15, undersea earthquakes, only 1 have caused tsunamis, so it is less than 1%. In addition, we can say with certainty that earthquakes of magnitude 6 and below are basically impossible to cause tsunamis. If your home is in Tianjin, in Shanghai, in Zhejiang, and there are earthquakes of magnitude 6 and magnitude 5 near the coast, don't worry about being associated with tsunamis. Tell you, it was this earthquake that caused not only a tsunami, but also a shock to the whole earth, just like a big fat man who stopped to breathe after running. Why? Because the whole earth is an elastic body, it can't help vibrating and shaking under the excitation of a big earthquake. As we all know, when we knock at Dazhong Temple, the bell rings ten miles away. Why? Why is it always noisy? Because it knocks on the earth, the energy is strong. Here is a dynamic demonstration of the tsunami, which was provided by the Environmental Center of the State Oceanic Administration. What? That is, the waves spread outward layer by layer. At the beginning of the water wave, you see the middle of the water falling and the gap spreads outward.

Then let's talk about the causes of the tsunami. Just now we talked about the submarine earthquake, which is one of the causes. In addition, there are volcanic eruptions, which can also cause tsunamis, especially submarine volcanoes; Another is the landslide under the sea. The sea floor is the same as the land we see. There are mountains below, as well as some plateaus. They may collapse for various reasons, causing a shock to the sea. Explosions and nuclear explosions under the sea are no longer carried out. A few years ago, first there was a nuclear explosion in the air, and then there was an underground nuclear explosion in the ocean. Now they are all underground because of the great pollution to the environment. Such an explosion under the sea floor, artificial explosion will also trigger a tsunami. Some of us don't "fry fish" in the river with explosives, why do we want to catch fish, and the waves that everyone sees are also rolling; Another is the falling of celestial bodies. If a comet or a meteorite hits the sea, it will burn itself as it is failing, carrying its remaining energy into the sea, which will also trigger a tsunami. We have mentioned these five kinds above, but the most important one is the earthquake and tsunami, which is caused by the earthquake, accounting for the vast majority.

Let's turn to the second question, tsunami. Earthquakes only give energy, but tsunamis cause damage. Here, I will give you an idea of the scale of tsunami source, which is caused by earthquakes.