The Luding earthquake has caused 74 people to be killed. Earthquake experts: In the future

In the next few years, a magnitude 9 earthquake may occur again worldwide

It should improve the prediction of the danger of earthquakes

At 12:52 on September 5th, a magnitude 6.8 earthquake occurred in Luding County, Ganzi Tibetan Autonomous Prefecture, Sichuan. The depth of the earthquake was 16 kilometers. After the earthquake, the communication with the outside world was interrupted. In addition, affected by the earthquake, the infrastructure of water, electricity, and transportation near the earthquake and nearby.

After the earthquake, the Sichuan Earthquake Administration immediately launched an emergency response to the secondary earthquake and made every effort to organize personnel search and rescue. According to official reports, as of 21:00 on September 6, the earthquake has killed 74 people. Among them, 40 people in Ganzi Prefecture were killed, 14 were lost, and 170 were injured; 34 people in Ya'an were killed, 12 were lost, and 89 were injured.

According to the China Earthquake Network speed report, as of 7:0:00 on September 7, a total of 13 aftershocks were recorded at level 3.0 and above. At present, the largest aftershocks are level 4.5, which occurs at 2:42 on the 7th. The city of Asusa County, the depth of the earthquake is 11 kilometers.

Regarding the cause of the earthquake and the broken belt, how to view the frequent earthquakes in the western region of China in recent years, Sun Shizheng, a researcher at the China Earthquake Network Center Center, accepted an exclusive interview with China News Weekly.

Qianyuan earthquake is destructive

Sometimes related to the Lushan Earthquake

China News Weekly: Compared with the earthquake in China in recent years, the number of victims caused by this Sichuan Luding earthquake is more. What are the reasons behind this?

Sun Shizhen: This earthquake occurred near Moxi Town, Luding County, Ganzi Prefecture, Sichuan Province. The depth of the earthquake was 16 kilometers, which belonged to the Qiyuan earthquake and was destructive. Generally speaking, the most destructive earthquake in the earthquake area occurs at about 10 kilometers below the ground. As the depth of the earthquake deepen, destructiveness will continue to decay. On the other hand, the deeper the depth of the earthquake, the wider the spread of earthquake waves. The depth of the earthquake at this earthquake is 16 kilometers. Big, a strong sense of shock in the distance. Some reports show that there are obvious shaking of high -rise buildings in some areas. This is because when the earthquake wave spreads here, its amplitude is exactly the same as the amplitude of the building itself, so it has formed resonance. From the perspective of earthquake prevention and disaster reduction, in the future, the earthquake resistance capabilities of these high -rise and ultra -high -rise buildings must be strengthened.

After the earthquake, there was a falling stone in the Gas Barrack Highway section of Lengyu Town, Luding County. (Picture source: Zhongxin.com)

China News Weekly: The freshwater river is in this earthquake. One area. China Earthquake Network News, since 1900, within 200 kilometers near the earthquake, a total of 6 earthquakes occurred by magnitude 6 or more. A large earthquake recently occurred in the Ya'an Lushan magnitude 7.0 earthquake in April 2013. Does the earthquake belong to the Yueshan earthquake?

Sun Shizhen: After the Lushan earthquake in 2013, in recent years, there are often 5 and 6 earthquakes in this area, but the academic community is still controversial whether the aftershocks of the Lushan earthquake can be called the Lushan earthquake. This time, a magnitude 6.8 earthquake in Luding in Sichuan can only be said that there is a certain correlation with the Lushan earthquake in time and space. Further research in combination with earthquake waves and seismic sequence types.

In addition, why is the seismic activity in the area so active? Because this area belongs to the Longmen Mountain Fracture Band, the Fresh Water River Fracture Belt and the Anning River-the Muhe River Fracture Belt and other fracture bands. The geological structure is more complicated, the stress accumulation is relatively strong, and the stress state is relatively complicated. After magnitude 6 and 7 earthquakes occur in this area, the release cycle of earthquake energy may be longer. Therefore, it is necessary to further study the mechanism and rupture of different earthquakes in the region. Moreover, for nearly 10 years, all magnitude 6 earthquakes have been put together to conduct overall research, and we cannot see it in isolation. For example, the Lushan Earthquake and the 2008 Wenchuan earthquake in 2013 both occurred on the broken belt of Longmen Mountain and were in the same stress state.

China News Weekly: Several earthquakes you mentioned are related to Bayan Kara blocks. The Bayan Kara block is located in the north of the main area of ​​the Qinghai -Tibet Plateau. It is one of the most strong crustal movements in the Qinghai -Tibet Plateau today. Since its historical records, the blockbuster border has continued to have a strong earthquake zone. In fact, this Luding earthquake is the third magnitude 6 and above earthquake in Sichuan Province since this year. The first two earthquakes were magnitude 6.1 earthquakes occurred on June 1, respectively. A magnitude 6.0 earthquake occurred in the city of Malcon. The earthquakes have also occurred on the border or inside of the Bayan Kara land. As early as ten years ago, some studies have shown that Bayan Kara block is in a period of active. Does this mean that this body will be there in the Southwest earthquake?

Sun Shizhen: From the Great Earthquake in Kunlun Mountain in 2001 to the 2008 Wenchuan earthquake, it has been related to the intensified activities of the Bayankara plot. However, according to the monitoring of the earthquake activity in the area in the past 10 years, I think that Bayan Kara blocks The body is currently at the end of an active period, and the energy has been released. In recent years, monitoring has found that the level of earthquakes in the region have been significantly attenuated, and gradually decreased from level 8 to level 7 and level 6. Since this year, several earthquakes in Sichuan Province can be understood as the adjustment stage of the land. Essence Compared with the Bayankara plot, I am even more worried that China may have a large earthquake of about 8 magnitude 8 in the next few years, because China has occurred in the 1950s and the first years of the 21st century. Several magnitude 8 earthquakes. But where happens, it is still difficult to predict. I don't think it will happen in the Sichuan area. In the previous seismic blank areas, or the South China region, the southeast coast and other places where there have been no major earthquakes for many years, it is worthy of focus.

The first night after the earthquake in the ancient town of Luding County. (Picture source: Zhongxin.com)

A magnitude 9 earthquake in the next few years may occur again in the world may occur again

China News Weekly: From the perspective of global standards, what is the level of earthquake activities this year? Can you make some predictions in the future?

Sun Shizhen: In terms of global standards, the level of magnitude 7 or above the global level of the world this year is significantly lower than in previous years. So far, only three earthquakes in the world have only occurred in the world. Generally speaking, it will occur about 18 times a year. Irregular. I think the main reason is that the outbreak of the Tangjia sea floor in January this year. The energy it released is equivalent to a magnitude 9.3 earthquake, and a magnitude 9 earthquake is equivalent to 32 magnitude 8 earthquakes. These energy comes from more than 100 kilometers inside the crust, which will inevitably lead to a relatively weakened energy release related to the earthquake, but this effect will not last too long.

The volcanic eruption reflects the activity inside the crust. It can be observed that since the beginning of the 21st century, the energy strength of the global crustal movement has been significantly lifted. The result of its impact is not only earthquake activities, but also a series of changes such as climate change. In the short term, in recent years, the Indian sector activities that have a greater impact on China have been relatively stable. The Indian sector is advancing at a rate of about 5 cm each year compared to the Eurasian sector. When the two sectors are interacted, the internal stress accumulation may be generated within some points, and an earthquake will occur to a certain extent.

If the time is stretched, a magnitude 9.1 earthquake occurred in Indonesia in 2004, a magnitude 8.8 earthquake occurred in Chile in 2010, a magnitude 9.0 earthquake in Japan in 2011, and three magnitude 9 earthquakes in seven years. After 2011, the global earthquake activities are generally less. From the beginning of the Ming Dynasty, the world may enter a new round of earthquakes. It is expected that a magnitude 9 earthquake may occur again in the next few years.

China News Weekly: In this context, from the perspective of preventing earthquakes, we should conduct seismic predictions and early warnings, should we conduct medium and long -term seismic risk assessments nationwide, and based on this, some preventive measures are taken in advance?

Sun Shizhen: China drawn the first generation of earthquake intensity regions as early as 1957, which is an effective risk assessment method. The intensity is different from the magnitude of the earthquake. The degree of destruction of the earthquake on the surface and various buildings is measured. Therefore, according to factors such as historical earthquake data and geological environment of various places, and combined with local population, economy and other indicators, it can be comprehensively developed nationwide to develop nationwide The inner intensity area has been adjusted every ten years, and it has been updated to the fifth generation.

However, a problem is that since the fourth generation of 2001, it is no longer called earthquake intensity region. It is renamed as a diagram of the seismic parameter area. The main change is to replace the intensity with the acceleration of the ground vibration vibration. During the earthquake, when the surface movement reaches a certain acceleration, it will cause the house to collapse. Therefore, this set of parameters are more from the perspective of the house shock resistance, which is conducive to the construction planning and construction engineering selection of earthquake resistance. This is its advantage, but the seismic parameters There are also certain limitations. These acceleration data mainly come from some buildings or engineering accelerators such as houses, bridges, dams, etc. This instrument can observe the data related to the earthquake. Level may bring some problems.

From the perspective of practical inspection, the effect of the third -generation intensity zone drawn in 1990 is relatively good, and the risk level is close to that of the national earthquake activity in the next decade in the next decade. In the above areas. From the perspective of risk assessment, in the future, we should consider how to effectively improve the prediction of earthquake risk.

Reporter: [email protected])

Edit: Du Wei

Operation editor: Wang Lin

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