5. 12 Wenchuan earthquake has no prediction at all?

After the 7.8 earthquake in Wenchuan County, Sichuan Province, the question "Why can't it be predicted before the earthquake, but it can be predicted after the earthquake" has become the focus of public attention. In response to this question, researcher Ding, chief earthquake prediction expert of Fujian Seismological Bureau, gave an answer here today. He said that it is difficult to make predictions before earthquakes, and earthquake prediction has become a recognized scientific problem in the world. The difficulty of earthquake prediction is much greater than originally thought, and the progress of earthquake prediction is much slower than originally thought. It can be considered that the level of global earthquake prediction is still quite low. The researcher analyzed that it is difficult to predict earthquakes before earthquakes, mainly because: first, the complexity of the seismic physical process itself and the "impenetrability" of the earth's interior. Earthquakes are natural phenomena on the earth, and the occurrence of earthquakes is also a complex seismic physical process. Because there are too many unknown factors in the process of earthquake preparation, the focal state before the earthquake and the fine structure inside the earth cannot be directly detected, and the crustal rupture process is very unstable. Even if human beings have a high level of simulation experiments, they are far from the real environmental conditions of the source, and in fact, they cannot simulate the rupture of extremely heterogeneous media in the crust on a scale of hundreds of kilometers. Secondly, the preparation and occurrence of earthquakes are the accumulation and release of strain caused by the stress on rocks in the crust, and the force source that causes its physical process and strain accumulation is the result of superposition and repeated action of many factors. At present, it is difficult to understand the relationship between their evolutionary processes. Moreover, large earthquakes are small probability events, which are difficult to repeat and test. Most of the so-called precursory phenomena before earthquakes are not in one-to-one correspondence with the actual earthquakes, so there is some uncertainty. Ding said that after the earthquake, the time, place and intensity of the earthquake (currently within one minute in Fujian) can be quickly and accurately determined through the modern instrument observation and data processing system of the seismic station. However, after a destructive earthquake or an influential earthquake, it is generally necessary to determine the post-earthquake trend to determine whether a destructive earthquake may occur in the short term. It should be said that the overall level of earthquake prediction at this stage is still very low, and there are still some sudden earthquake events. After all, earthquake prediction research is still being explored.