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Today, human beings have pointed out many technologies on the scientific skill tree, such as space exploration. Human-made aircraft have already flown out of the solar system; and Mars rovers in the United States and China have already sent back a lot of data on Mars.
You must know that Mars is also 55 million kilometers away from the earth at the nearest distance, and the farthest is more than 400 million kilometers, with an average distance of 220 million kilometers . Landing a probe on the surface of Mars across hundreds of millions of kilometers is incredible. Humans can achieve such difficult things, but they cannot predict earthquakes.
Human technology is so advanced, why can't we predict earthquakes?
Predicting earthquakes, even with today's advanced technology, is still an elusive thing. Although to a certain extent, humans can predict the probability of an earthquake in a certain place, the intensity of the earthquake, and the loss, etc. ; but if you predict the specific time of the earthquake, humans are helpless.
Because of trying to predict earthquakes, we face many difficulties. The reasons for the earthquake are intricate and complicated. During the period, factors such as the focal depth and epicenter distance affect the . It is basically impossible to accurately predict the location and time of the earthquake.
Humans cannot accurately predict earthquakes
Aside from the influence of various external factors, the fundamental reason why humans cannot predict earthquakes is that they cannot see .
In fact, human predictions of many things are based on what is visible. For example, in weather forecast, the satellite captures the movement of the cloud, and then predicts its route in advance, so as to predict the weather in a certain area .
To expand the field of vision a little more, human beings predict whether comets and asteroids will hit the earth. They also use various space observation instruments to see the arrival of "other things" in advance and predict their orbits.
The Earth's Internal Structure
Earthquakes originate from the movement of magma inside the earth and the collision or rupture of crustal plates. To predict earthquakes, we must see the motion trajectories of magma, plates and crust in the depths of the ground. But the deepest well that human beings have drilled so far is only about 10 kilometers, and the radius of the earth is 6371 kilometers!
In a word, can not directly observe the epicenter and crustal structure, so humans cannot predict the occurrence of earthquakes .
Affected Scope of Seismic Waves
An earthquake of magnitude 4.8 occurred in Wenchuan, and Chengdu received an early warning 19 seconds in advance
At 23:36 on July 14, Beijing time, an earthquake of magnitude 4.8 occurred in Wenchuan County, Sichuan Province. Fortunately, there were no casualties. Then there were news reports that Wenchuan earthquake occurred in Chengdu and received an early warning 19 seconds in advance. Many residents living in Chengdu have received early warning messages from the China Earthquake Warning Network.
Since earthquakes cannot be predicted, why did receive warnings 19 seconds in advance in Chengdu?
Earthquake Warnings Received by Chengdu Residents
Before answering this question, let's first understand the concept of seismic waves. Seismic waves are the fluctuations generated during earthquakes, which can be divided into three types according to the propagation mode: longitudinal waves, transverse waves and surface waves.
Longitudinal wave (also known as P wave) is the vibration that reaches the ground longitudinally from the depths of the ground. Its propagation speed in the crust is 5.5 to 7 kilometers per second. Although the speed is fast, the damage is very small. Because its form of vibration is up and down, it will not have much impact on the ground.
The transverse wave (also known as the S wave) can be simply understood as the vibration that propagates laterally. The propagation speed of is 3.2 to 4.0 kilometers per second. It can make the ground shake back and forth, left and right, and is very destructive. Mixed waves that meet at the surface are the main cause of building collapse in earthquakes.
When an earthquake occurs, the seismic waves from the epicenter and epicenter are like waves advancing, and it takes a certain amount of time to spread around. And the epicenter of the earthquake is about 76 kilometers away from Chengdu, and it takes more than ten seconds for the seismic wave to reach .
Seeing this, everyone should understand that the warning messages received by people in Chengdu were issued after the earthquake. It is understood that 5 seconds after the Wenchuan earthquake with a magnitude of 4.8, the China Earthquake Prediction Network will send out the news, so people can receive early warning .
Seismic wave propagation mode
Extended reading: China had correctly predicted the earthquake
At 19:36 Beijing time on February 4, 1975, a magnitude 7.3 earthquake occurred in Haicheng . This is the largest earthquake in the history of the central and southern part of the Liaodong Peninsula, but the number of casualties caused by the earthquake is very small.
Because before the earthquake, Chinese scientists accurately predicted the earthquake and released the forecast in time, which greatly reduced the severity of the disaster; The Haicheng earthquake totaled 18,308 casualties, accounting for 0.22% of the total population of the region. Under the power of the 7.3-magnitude earthquake, the number of casualties was very small.
Moreover, the Haicheng earthquake is generally considered to be the only successful case in human history where large-scale evacuation was organized by the government on the basis of correct prediction of the earthquake, which greatly reduced casualties and losses.
It's worth noting that here is talking about predicting earthquakes correctly not . and based on long-term monitoring, combined with foreshocks, earthquake fault zones and other factors, make a rough prediction . At that time, Chinese scientists predicted that an earthquake would occur in the area, but did not know the exact time and location of the earthquake.
Written at the end
Being able to predict earthquakes is the dream of many scientists. Unfortunately, humans have so far been unable to accurately predict when and where earthquakes will occur.
We believe that one day in the future, with the efforts of scientists, there will be breakthroughs and innovations in earthquake prediction technology. By that time, perhaps humans will be able to predict earthquakes as accurately as the weather.
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