Now that science and technology are so advanced, why can't we predict earthquakes?

In the field of seismology, "earthquake prediction" mainly refers to the scientific prediction of the location, time and magnitude of possible earthquakes made by the seismological department by using the existing seismic instruments and monitoring means, which is generally used to judge the long-term situation of earthquakes-for example, Nepal is located in the collision zone between India-Australia plate and Eurasia plate, so the possibility of earthquakes here is of course greater in the long run, which is also in line with the article that some scientists predict that a major earthquake will occur in Nepal. "Earthquake prediction" is used to warn of short-term or even impending earthquakes. What we usually care about is the "short-term and imminent prediction" of earthquakes, and we hope that after the prediction is issued, we can escape in time before the earthquake occurs. Since 1966, China has made successful examples of earthquake prediction in Haicheng earthquake and Songpan earthquake. Earthquake prediction is still an unsolved worldwide problem, and countries are still actively exploring and studying, and only a few earthquakes can be predicted. At present, the difficulty of earthquake prediction has not been overcome, and earthquake prediction can only predict earthquakes of a certain magnitude in a certain area for a period of time. Earthquake prediction that accurately describes the time, place and magnitude of an earthquake is likely to be a rumor.

Why not make earthquake prediction, just like weather prediction?

We are used to learning advanced technology from earthquake-prone Japan, but do you know that Japan has given up the illusion of earthquake prediction and returned to the reality of disaster prevention? The important reason is that earthquake prediction is difficult to do. The difficulty of earthquake prediction actually comes from people's ignorance of earthquakes. Teng Jiwen, an academician of the Chinese Academy of Sciences and a researcher at the Institute of Geology and Geophysics of the Chinese Academy of Sciences, said that earthquake prediction has three major difficulties:

One is the impenetrability of the earth's interior. Up to now, the deepest drilling is the ultra-deep drilling in kola peninsula, the former Soviet Union, which reaches 12km. Compared with the average radius of 6,370km on the earth, it is still "superficial" and still cannot solve the problem of direct observation of the earthquake source.

The description of earthquakes in academic circles still stays in the qualitative statement given by Li Siguang that "local underground energy will explode when it accumulates to a certain extent", but there is no quantitative statement. In other words, we don't know how much energy is needed to trigger an earthquake. The critical point of an earthquake is how much energy is gathered, which cannot be solved in a short time and has no theoretical support. Seismologists vividly compare this situation to the initial stage of understanding the earth. According to Chen Xuezhong, a researcher at the Institute of Earthquake Prediction, Seismological Bureau of China, what is the mechanism of earthquakes? We can't go underground to find out, just as heaven is easier to go underground.

The second is the infrequent occurrence of major earthquakes. Up to now, the research on precursory phenomena before large earthquakes is still in the stage of summarizing and studying various earthquake cases, lacking practical and reliable empirical laws necessary for establishing the theory of earthquake occurrence.

Thirdly, the complexity of seismic physical process. The earthquake process is a highly nonlinear and extremely complicated physical process. The complexity and variability of earthquake precursors may be closely related to the complexity of the geological environment in the source area and the high nonlinearity and complexity of the earthquake process.

Learn from Japan: prevention is better than prediction!

Japan, located in the Pacific Rim seismic belt, is a world-famous earthquake-prone country. In Japan, the annual national unified "Earthquake Disaster Prevention Day" is even as vigorous as a festival. Like China now, the Japanese people, who have suffered from frequent earthquakes, have placed infinite expectations on earthquake prediction. They believe that as long as our technology is advanced enough, the clues of earthquakes will always be captured in advance. 1965, the research on earthquake prediction in Japan was officially launched, and the experts undertaking related scientific research projects followed the "prediction possibility theory" in unison. At that time, forecasting research became a cash cow, with a total investment of 200 billion yen. Later, with the gradual understanding of the complex mechanism of earthquakes, the hope of short-term prediction is becoming more and more slim. 1962' s survey report on the present situation of earthquake prediction and development planning states that "a very reliable prediction will be made after 10", but it seems that it cannot be fulfilled now.

Worldwide, earthquake prediction was the mainstream direction of earthquake research in many countries in the 1970s, and it was not until the 1990s that this direction was re-examined. At that time, an expert group in California made a prediction of the 1992- 1993 earthquake, but the prediction failed. However, it finally makes people rational, and the academic circles all over the world begin to accept the fact that it is impossible to predict earthquakes in the near future at present.

Although it took a detour, after the change of ideas, Japan's scientific research process has obviously accelerated its pace. Taking the Hanshin earthquake in 1995 as an opportunity, the Japan Meteorological Agency expanded the observation points of strong earthquakes in China to about 600. The Ministry of Science and Technology has also laid a nationwide seismic observation network consisting of 65,438+0,000 seismometers. In this way, the distribution of seismic intensity can be obtained correctly and quickly by installing a strong earthquake instrument with a density several times higher than that in the past, which is a great progress. After the Great Hanshin Earthquake, the Japanese government re-examined the national countermeasures for earthquake prevention and disaster reduction, and the Law on Special Measures for Earthquake Prevention and Disaster Reduction came into being, changing the term earthquake prediction research, which has been widely used, into earthquake investigation and research. The seismic design and seismic monitoring system of Japanese buildings have also changed the previous concept. In the past, the research on earthquake precursors only focused on specific areas, but now it has been extended to the whole country. Many enterprises in Japan, such as railway and electric power system, have taken the lead in adopting disaster prevention measures that do not depend on prediction. Japan Railway Corporation has set up seismographs at stations along the line and introduced automatic devices, which can stop the whole train when abnormal values appear.

Since earthquakes are unpredictable, should we just sit back and wait?

Jones, a famous structural geologist, once said, "Would you rather escape from the building an hour earlier, or hope that the house won't fall down at all?" Japanese scholars have also said that the most dangerous time of an earthquake is when there is no earthquake. There are few casualties directly caused by the earthquake, and most of them die from secondary disasters, such as the collapse of houses. An important reason for the heavy casualties caused by this earthquake in Nepal is that the epicenter is close to Kathmandu, the most densely populated capital of Nepal, and the seismic capacity of local houses is generally poor, so it is difficult to resist such a strong earthquake. When we don't have effective methods to prevent earthquakes, the best measure we can do is not to expect earthquakes, but to be prepared for danger in times of peace and nip in the bud. Only by strengthening buildings in daily life and reaching certain seismic standards can casualties be minimized.

In addition, it is also very important to do a good job of "earthquake early warning". "Earthquake early warning" is an evacuation alarm when the local earthquake wave reaches a place farther away from the source, that is, when the earthquake has already occurred, but it is also a truly effective means of disaster prevention, which we need to focus on. When a major earthquake occurs, seismic stations near the epicenter of the major earthquake first receive seismic waves. At this time, an alarm signal will be issued immediately. Because the electromagnetic wave travels very fast, the remote area can know that a major earthquake has occurred before the arrival of the seismic wave, and immediately take evasive measures to reduce casualties.