What are the characteristics of tsunami?

What are the characteristics of tsunami?

Tsunami is a powerful and destructive wave. When there is an earthquake on the seabed, the sea water fluctuates violently due to the power of seismic waves, forming powerful waves, moving forward and flooding coastal areas one by one. This is the so-called tsunami.

When the earthquake occurred, the seabed strata broke, and some strata suddenly rose or sank, which caused the whole water layer from the seabed to the sea surface to "shake" violently. This "jitter" is very different from the waves you usually see. Generally, waves only fluctuate near the sea surface, and the depth involved is not large, and the amplitude of waves decays rapidly with the water depth. The sea water "jitter" caused by earthquake is the fluctuation of the whole water body from the bottom to the sea surface, which contains amazing energy.

The height of the wild waves caused by the tsunami can reach 10 meters to tens of meters, forming a "water wall". In addition, the tsunami has a large wavelength and can travel thousands of kilometers with little energy loss. For the above reasons, if the tsunami reaches the shore, the "water wall" will rush to the land, posing a serious threat to human life and property.

Tsunami refers to the huge waves of hundreds of kilometers caused by submarine earthquakes, volcanic eruptions, underwater landslides and collapses. Its performance in coastal areas is that the sea water rises sharply, suddenly forming a "water wall", which, accompanied by rumbling noise, instantly invades coastal land, engulfs fertile fields and towns, and then the sea water suddenly recedes, or rises first and retreats, and sometimes appears repeatedly, causing huge loss of life and property. Before the arrival of tsunami waves, local tsunamis are often accompanied by strong earthquakes or earthquake disasters. China is also a country with frequent storm surges. The tide level anomalies expressed by storm surges, earthquakes and tsunamis have been called tsunamis, sea overflows or great tsunamis in past dynasties. In recent 20 years, Chinese academic circles have decided to call the tidal level anomalies caused by storms and earthquakes storm surges and tsunamis respectively. In addition, sometimes disasters caused by astronomical, storm, earthquake and other abnormal tidal levels are collectively referred to as "tidal disasters". But in most cases, the so-called tidal disaster habitually means that the initial rise of the water surface near the tsunami source in the ocean is only 1 to 2 meters during the storm surge disaster. When the waves migrate in the deep sea, the wavelength can reach tens to hundreds of kilometers, the period can reach 200 minutes, and the most common thing is that it can reach nearly 1000 kilometers per hour. Therefore, the tsunami will not cause disaster in the deep sea, and it is even difficult to detect such fluctuations. However, when the tsunami wave enters the continental shelf, its depth becomes shallow sharply and its energy is concentrated, resulting in its amplitude increasing. If the continental shelf is very narrow, tsunami waves with almost the same speed from the sea surface to the seabed will carry huge energy to the shore or harbor, and the wave height will suddenly increase. At this time, there may be a huge wave with an amplitude of 20-30 meters, which will cause the peak to roll back. This huge wave rushed there, and it was in ruins. It is in these places that the tsunami has become the greatest threat to life and a terrible natural phenomenon.

After reading the article, do you know what the characteristics of tsunami are?

Tsunami, love

The whole world is taking action, saving innocent refugees in the disaster area with money, money and strong power.

The total donations from countries affected by the Indian Ocean earthquake and tsunami have risen to $2 billion. Sports stars donated money to the disaster area. Basketball circles in China raised 260,000 yuan in relief funds for tsunami-stricken areas; Little O 'Neill personally donated $55,000 to the tsunami victims; Schumacher, a German driver who won the F 1 seven times, donated $ KLOC-0/00000 to the Indian Ocean tsunami disaster area. Bayern Munich Club donated 300,000 euros to the tsunami-stricken areas ... People from all regions also gave their love. Tianjin tsunami donation has reached nearly 5 million; Dutch people donated more than 654.38 billion euros to the tsunami-stricken areas; Germany's private donation to tsunami victims in South Asia has exceeded 500 million US dollars. Guangdong people donated more than 654.38 billion yuan to the tsunami-stricken areas ... Rich people and ordinary people are giving generously. Ding Lei announced in Guangzhou that he would donate $6.5438+0.2 million (equivalent to RMB 6.5438+0.00 million) to China Red Cross Society in his own name. Pan Shiyi donated 6,543,800 yuan, a set of real estate with a value of 6,543,800 yuan; Hui donated 5 million yuan to the Indian Ocean tsunami disaster area in Beijing; 70-year-old grandmother donated 1000 yuan, leaving no name ... singers and movie stars are not to be outdone. Hong Kong film and television superstar Jackie Chan publicly donated HK$ 500,000; China entertainment circle mobilized a charity performance for one night and raised more than 30 million yuan; Stephen Chow canceled the celebration and donated 500,000 yuan; Andy Lau also donated 300,000 to celebrate the Golden Horse Award; Singers such as Joey Yung, Nicholas Tse and twins donated 630,000 yuan. ...

These data tell us that there is great love all over the world. "As long as everyone gives a love, how beautiful the world will be ..." The familiar song echoed in my ears again.

After watching Escape from the Tsunami, you will know what the characteristics of the tsunami are.

Shouting that there is a fire, let the villagers run out and tell them.

What are the signs before the tsunami?

The omen before the tsunami.

These four macroscopic precursor phenomena are caused by the mechanism of tsunami occurrence and spread. If there is an earthquake at the bottom of the sea, it will cause large-scale seawater sinking, and the coastal areas near the epicenter will have an abnormal sudden retreat of seawater. If the earthquake causes a large-scale uplift of the seabed crust, it will cause a large-scale accumulation of seawater and an abnormal surge of seawater in the coastal areas near the epicenter.

There are several abnormal characteristics of abnormal high tide in seawater: the time of high tide in seawater is inconsistent with the usual time of high tide in seawater; The speed of seawater recession is much faster than usual; The sea water recedes greatly, often falling below the lowest tide line or rising above the most * * * line.

In the coastal areas hundreds of kilometers away from the epicenter, you can see the abnormal sudden retreat or surge of seawater, but it is not easy to see it in the coastal areas a few kilometers away from the epicenter. After an earthquake, the time for the seawater to suddenly retreat or swell varies according to the distance from different places to the epicenter. Some are just after the main earthquake, and some are 10-20 minutes after the main earthquake. The interval between the sudden retreat or surge of sea water and the tsunami landing is also long and short, and there are only a few short ones.

Tsunami wave is a gravity long wave with a wavelength exceeding 100 km. Its propagation speed is equal to the square root of the product of gravity acceleration (9.8m/s) and seawater depth, so the deeper the seawater, the faster the tsunami wave speed, and the shallower the seawater, the slower the tsunami wave speed. When the tsunami wave enters the shallow sea area near the coast from the deep sea area far away from the coast, the wave speed drops sharply, and the wave speed behind it is still very fast, so the back wave catches up with the front wave, and the front wave and the back wave are superimposed, which doubles the wave height. Ships in shallow waters will suddenly and violently bump up and down; There will also be a huge, amazing and terrible roar on the sea. The four precursor phenomena are signs of approaching tsunami and disaster warning signals, warning people that the tsunami is about to land. If they want to survive, they should run to high places as soon as possible, otherwise they will be swallowed up by huge waves in ten minutes, as short as several minutes, or even only a few tens of seconds.

The omen before the earthquake.

At present, earthquake disasters cannot be accurately predicted. However, long-term observation and research show that there will be some signs before the earthquake, which can remind people to be vigilant. These signs mainly include:

1. Animals are abnormal: for example, a large number of snakes climb out of holes for long-distance migration; Poultry and livestock do not eat, drink, bark or enter the nest; During the day, a large number of mice come out of the hole, not afraid to catch up; The animals in the zoo are depressed and can't afford to wait.

2. Groundwater anomalies, such as sudden water in dry wells in earthquake areas, sudden rise or sharp drop of water level in well water, and change from bitter to sweet and from sweet to bitter.

3. Ground light and ground sound appear: In a short time before the earthquake, the earth often suddenly emits colored or strong ground light, or it may emit a loud noise like a train passing by or thunder.

4. Some people also have abnormal emotions: before the earthquake, some people also had abnormal emotions, especially the elderly, children and patients.

How to adjust the drift? A novice fisherman humbly asked his teachers for advice.

Depending on the number of drifts, choose the right amount of bait, with the hook as the bottom or the empty hook as the bottom.

You should know that the steady state after the drift purpose is changed is 4 eyes.

Then the float is pulled down by a drift length to form a floating bottom. Adjust the hanging bait to make the drift aim at 2 eyes, pay attention to the weight of the bait, and throw it several times to remember the change of weight on the drift aim.

Float the float in its original position. Empty hook status is 4 mesh. Hanging bait floats in 2 meshes. This is the best bleaching method.

It should help you! Remember to like it! ! !

People's reaction to the tsunami.

Usually, if the sea water on the shore increases or decreases abnormally, it indicates that a tsunami is coming. In the event of a tsunami, people on the shore should move from low-lying areas to higher-lying areas as soon as possible. Ships sailing at sea must not return to the port at this time, but should sail to the deep sea area.

When the earthquake occurred: 1. For the personal safety of yourself and your family, please hide under solid furniture such as tables.

The shaking time is about 1 min. This is the first thing that should be considered is the personal safety of yourself and your family. First, hide under a solid table with a low center of gravity and hold the legs tightly. In places where there is no table to hide, protect your head with cushions and other things anyway.

2. Turn off the fire immediately when shaking, and put out the fire immediately in case of fire.

When there is a big earthquake, there will also be situations where you can't rely on fire engines to put out the fire. Therefore, the efforts of each of us to turn off the fire is an important factor to control the earthquake disaster to a minimum.

Get into the habit of turning off even a small earthquake.

In order to prevent the fire from causing great disaster, it is self-evident that it is extremely important for the family to help each other and put out the fire early.

During the earthquake, there were three opportunities to turn off the fire.

The first chance is that a big earthquake occurs before a small one.

At the moment when they felt the small shaking, they immediately greeted: "Earthquake! Turn off the fire! " Turn off the heating stove, gas stove, etc.

A second chance after the earthquake stopped.

Turn off the fire as soon as there is a big shake, and the kettle on the gas stove and heating stove will slide down, which is very dangerous.

When the shaking stopped, he shouted again, "Turn off the fire! Turn off the fire! " Turn off the fire.

The third chance was after the fire.

Even if there is a fire, it can be put out within 1-2 minutes. In order to put out the fire quickly, always put the fire extinguisher and bucket near the fire point.

Don't panic and run outside.

After the earthquake, running out in a panic, broken glass, roof tiles, billboards, etc. are very dangerous. Fall down and hit you. In addition, cement prefabricated walls and vending machines are also in danger of collapse. Don't go near these objects.

4. Open the door and ensure the exit.

Houses with reinforced concrete structures, etc. Has been locked in the house because of the dislocation of doors and windows caused by earthquake shaking. Please open the door and ensure the exit.

Usually, you should think about how to escape if you are locked in the house, and prepare ladders and ropes.

5. In outdoor situations, protect your head and avoid dangerous places.

When the earth is shaking violently and unstable, people will have the psychology of helping and grasping something. Most of the doorposts and walls around you will be helped. However, these seemingly solid things are actually dangerous.

During the undersea earthquake in Miyagi Prefecture 1987, Japan, many people were killed or injured due to the collapse of precast concrete walls and doorposts. Don't * hide near cement precast slab walls, doorposts, etc.

In busy streets and buildings, the most dangerous thing is that things like glass windows and billboards fall and hurt people. Pay attention to protect your head with your hands or handbags.

In addition, pay attention to the situation that the vending machine falls over and hurts people.

In the building area, according to the situation, it is safer to enter the building to avoid.

6. In department stores and theaters, follow the instructions of the staff.

In places where there are many people in department stores and underground streets, the most terrible thing is chaos. Please follow the instructions of the store staff and security guards.

As far as earthquakes are concerned, it is said that underground streets are relatively safe. Even if there is a power failure, the emergency lighting will come on immediately. Please take action calmly.

In case of fire, it will be filled with smoke immediately. Take refuge in a low posture, and never smoke.

If you take the elevator

In case of an earthquake or fire, you can't use the elevator. In case there is an earthquake when you take the elevator, please press all the buttons on each floor on the operation panel. Once stopped, leave the elevator quickly and take refuge after confirming safety.

Elevators in high-rise buildings and recent buildings are equipped with devices to control operation. When an earthquake happens, it will automatically stop at the nearest floor.

If you are locked in the elevator, please contact the management room for help through the dedicated telephone in the elevator.

7. The car is parked on the side of the road, and driving is prohibited in the controlled area.

In the event of a major earthquake, the car will be like a flat tire, unable to grasp the steering wheel and difficult to drive. You must pay full attention to avoid the intersection and park your car on the side of the road. In order not to hinder the passage of evacuees and emergency vehicles, we should give way to the middle part of the road.

In the city ... >>

Was there any sound when the tsunami happened?

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