Recently, there was an earthquake along the coast of Japan. Experts predict that there will be another strong earthquake in the next week, which will lead to a huge tsunami. But when it comes to the earthquake in Japan, the most unforgettable thing is the earthquake and tsunami that occurred in Fukushima, Japan on 20 1 1. So what exactly is a tsunami? How did it happen? What does it have to do with earthquakes?
Earthquake/tsunami
Tsunami is essentially a huge destructive wave. Its wave speed is so fast that it can cross an ocean in a few hours. Moreover, its wavelength can spread thousands of kilometers of energy without loss. Because of its extremely fast speed and powerful tsunami, the disaster brought by it is devastating. Basically, wherever Shanghai waves go, they are swept away and in a mess. 20 1 1 The height of the tsunami triggered by Japan reached 10 meter, exceeding three floors. At that time 18850 people disappeared and died. However, in human history, there are even more terrible tsunamis.
I believe many friends still remember the Indian Ocean tsunami in 2004. At that time, it was really a national donation, and the impact of the tsunami was very serious. It is said that the tsunami at that time only lasted 10 minutes, but more than 2 million people were homeless. Nearly170,000 people died in Indonesia alone, and the population and property losses were very heavy.
Fortunately, this kind of tsunami does not happen frequently, usually once every 7- 10, and its location is generally consistent with the volcanic earthquake zone.
What is the relationship between earthquakes and tsunamis?
Many friends will find that many serious tsunamis are caused by earthquakes. Tsunamis are generally caused by earthquakes, landslides and volcanic eruptions, among which earthquakes are the most common causes. Therefore, the tsunami-prone area basically coincides with the global volcanic earthquake zone.
You can imagine a contrast scene. What's the difference between a sea tsunami and a land tsunami? On the sea surface, the tsunami is not particularly obvious, only tens of centimeters higher than the usual waves, but it can be several meters or even tens of meters higher on land. Why?
Compared with ordinary waves, the path of tsunami is slightly different. It forms a straight line and rushes forward, and the energy will burst in an instant, while the wave energy we see at the seaside is scattered. When the tsunami reaches the shore area, it will start to slow down when the bottom is blocked by the ground, but the speed at the top will not slow down, which is different from the sea level rise.
What should I do if the tsunami comes? Is the land safer or the sea safer?
Tsunamis, like waves, may rise again and again, but the frequency is lower and the interval is shorter than waves. The peaks of the two tsunamis may be separated by more than half an hour. When we are unfortunately hit by a tsunami, is the land safer or the sea safer?
As mentioned above, the power of the tsunami is very great, because it is fast and moves in a straight line, so when the tsunami rushes in, you are likely to be hit by the power of the tsunami at once, and you can only become a marionette of the waves, making you rise and let you fall. When the tsunami swept offshore, even cars and trees were swept away by the tsunami, and its power was obvious.
Therefore, when encountering a tsunami, we should still try to move higher than the land. Of course, for a particularly high tsunami, if it doesn't run fast enough, it may be swept away soon. When the tsunami came, hundreds of meters along the coast were dangerous areas. If you run on your legs, you may not win. If you are unfortunately involved in the sea, you must remember to catch suspended matter, avoid struggle and reduce your energy loss in the sea.
Summary:
As a coastal person, I actually encounter tsunamis quite often, and I am scared to death every time. Of course, although it is difficult to warn the tsunami, it will take some time to warn it through the monitoring of earthquakes and volcanic activities.
Don't be curious to stay on the shore when you observe abnormal sea water ups and downs.