Scientific understanding of the deep source earthquake to understand the mystery of the earth deep

At 01:00 on June 29, 2002, a magnitude 7.2 earthquake occurred in Wangqing County, Jilin Province. The depth of the earthquake was 540km, which belonged to the Shenzhen Earthquake. Compared with a large number of personnel casualties and major economic losses, the earthquake does not cause casualties and building destruction. The surrounding residents around Wang Qing near the epicenter did not even feel the occurrence of the earthquake. There are different degrees of shocks in some areas.

What is a deep source earthquake?

In order to study and classify the needs of the earthquake, the earthquake is divided into shallow source earthquake, Zhongyuan earthquake, and Shenyuan earthquake according to the depth of the earthquake. Among them, an earthquake with a depth of the earthquake within 60 kilometers is a shallow source earthquake; an earthquake with a depth of the earthquake from 60 kilometers to 300 kilometers is a mid -source earthquake; the earthquake with a depth of the earthquake is more than 300 kilometers. Deep shock). A magnitude 6.9 earthquake on June 29, 1934 occurred in the east of Sulawesi Island, Indonesia. The depth of the earthquake was 720km, which is the largest depth of the depth of depth recorded by humans so far. A magnitude 8.3 earthquake occurred in the Sea of ​​Ehiek on May 24, 2013. The depth of the earthquake is 609km, which is the largest shake -level deep earthquake recorded at present. From the perspective of distribution, almost all deep shocks are concentrated on the Pacific volcanic earthquake belt. Wang Qing, Hunchun and Heilongjiang Province in Jilin Province, Mu Emperor, Dongning, and Mudanjiang are the only Shenzhen -source earthquake areas in my country. There are data recorded at 7 or more in the data recorded on July 31, 1917. 7.5 Southeast Southeast 7.5, 1918 4, and 4, 1918 On the 10th of the June 10th, 7.2th level, April 10, 1940, Dongning 7.3, January 11, 1946, Ning Annan 7.2 levels, 7.7, September 29, 1973, September 29, 1973 In 2002, the most significant deep earthquake in Wang Qing's 7.2 deep shocks, in recent years, was the 6.4 -level deep shock that occurred in Linkou County, Heilongjiang Province on January 2, 2016.

How was the deep shock discovered?

Deep shock discovery can be traced back to the 1920s and 1930s. Japanese earth physicists and Daqingfu discovered in many island arc areas to discover the geometric form of the Zhongyuan earthquake. In the 1950s, American seismicist H. Beniov developed it into a system of systems. In the 1960s, with the rise of the theory of the sector, it was believed that it was related to the Pacific sector dived. It is also called the Beniov belt. Most of the earthquakes in the Beniov belt occur inside the dive section. The gaps are shallow earthquakes, tending to the island arc, and the mainland is a medium -sized earthquake in turn. The depth of the earthquake sources from the ocean to the mainland to the mainland is distributed in an orderly manner (as shown in Figure 1, Figure 2).

Figure 1 The distribution map of the earthquake above the 4th level of Japan to the 4th level of Northeast China (1964-2016)

Figure 2 P wave speed structure vertical section (red indicates low speed abnormalities, blue indicates high speed abnormalities, white dots are earthquakes)

How is the deep shock produced?

The dive effect of the Pacific sector affects the power process, the characteristics of the force field, and the structure movement inside the sector. It is generally believed that deep shocks are produced in the upper mantle near the plate boundary under the dive of the sector. Wang Qingshen took a dive on the dive belt below the Pacific sector to the northeast of my country. The cause of the Shenyuan earthquake is very complicated, so far there is no unified statement. There are many causes of deep earthquakes. At present, the possible cause mechanisms that are more arguing can be classified as three types: dehydration and crisp cracks, anti -crack fracture faults or phase -changing faults and thermal cutting effects caused by the phase change of olives.

What is the significance of studying deep shock?

The study of the dive belt of the sector has always been the forefront, hotspots and difficulties in the field of earth science. The deep -source earthquake that occurs on the dive belt of the sector has always been a major scientific issue that has been widely concerned by the international academic community. Deep shock plays an important role in studying the internal structure of the earth and the movement and dynamic mechanism of the sector. The deep shock activities in the northeast of my country and the occurrence of Changbai Mountain volcano with potential catastrophic eruptions and some shallow source strong earthquakes have possible correlations. The mechanism of studying deep shocks will help in -depth understanding of the driving mechanism and dynamic characteristics of the structure of the sector; study the characteristics of deep earthquake earthquake waves, can obtain important information and nature related to the deep structure of the earth, deepen the internal structure of the earth, deepen the internal structure of the earth know. These studies are of great significance for exploring volcanic activities and earthquake activities in the Northeast region and to guide disaster prevention and mitigation.

Is the deep shock related to the volcano?

Regarding the deep source earthquake and volcanic activities that occur in northeast my country, there are correlations, both are affected by the dive effect of the sector. Seismic analysis imaging results show that the Pacific sector dive the front edge of the Japanese trench has arrived at the junction of the Songliao Basin and Daxinganling in the northeast of my country (Figure 2). Specific earth dynamics environment and structural physical conditions determine the conditions for the occurrence of deep -source earthquakes, shallow source earthquakes and volcanic activities in the Northeast region. The deep earthquake areas of Wang Qing, Hunchun and Heilongjiang Province in Jilin Province, Mu Emperor of Heilongjiang Province, Dongning, and Mudanjiang are one of the two deep -seismic areas with a depth of depth of the global continent. Activities of the front edge of the front edge will also have a certain impact. For example, after Wang Qing's 7.2 deep shock in 2002, the Changbai Mountain Tianchi volcano appeared an obvious magma disturbance process from 2002-2005. Therefore, the deep shock has certain instruction significance for the research on the mechanism of studying the shallow source earthquake and volcanic activities in the Northeast. Wang Qing's 7.2 Shenzhen Earthquake is an active representation within the earth. The occurrence of deep shocks provides indispensable information for people to detect the deep ground core and mantle structure of the earth. After nearly a century of research, the Shenyuan earthquake seismic mechanism has not yet obtained the consensus of the scientific community, and the mystery of the deep earthquake is still yet to be solved!

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Source: China Earthquake Administration Public Service Department (Regulations Department)

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