A strong earthquake of magnitude 8.0 occurred in Wenchuan, Sichuan.
3 1 degree north latitude and 0/03.4 degree east longitude.
According to the report of the Ministry of Civil Affairs, more than 9000 aftershocks occurred on 3rd 12. The Wenchuan earthquake in Sichuan has caused 90,560 people to be killed, 352,290 injured, 2,6221missing and14,385,640 people to be relocated urgently. The cumulative number of people affected by the earthquake has reached 40,560+00000. As of June 24th, 12, * * has received donations of 2.61.01.000 billion yuan from home and abroad, of which 1.7 1.47 billion yuan was actually received, and 3.679 billion yuan has been allocated to the disaster area. There are 448 1.4 million disaster relief tents, 35,458 simple houses (1.7 1.24 more than the previous day), 2,465,438 quilts +0.9347 million beds, 3,304,526 pieces of clothes, 336,000 tons of fuel and 720 tons of coal. According to the report of the Ministry of Health, as of 24th 12: 00, 75,086 people were hospitalized due to earthquake injuries, 40,644 people have been discharged, 3,484 people have died in hospital, 23,864 people are still hospitalized, 4,274 people have been transferred from Sichuan to other provinces and cities for treatment, and a total of 289,457 injured people have been treated. The economic loss reached more than 1 108 billion.
The earthquake was caused by the rapid uplift of the Qinghai-Tibet Plateau caused by the subduction of the Indian plate to the Asian plate. The plateau material slowly flows eastward and squeezes eastward along the Longmenshan structural belt on the eastern edge of the plateau, encountering the tenacious resistance of the rigid block under the Sichuan basin, resulting in the long-term accumulation of tectonic stress energy, and finally suddenly released in Beichuan-Yingxiu area of Longmenshan. Thrust, dextral and compressional fault earthquakes. The seismogenic structure is the central fault zone of Longmenshan structural belt, which thrusts from southwest to northeast under the action of compressive stress. The earthquake was a one-way rupture earthquake, which moved from southwest to northeast, causing aftershocks to expand to northeast. After the main earthquake, the process of stress propagation and release is slow, which may lead to strong aftershocks and long duration. This is a shallow earthquake. Wenchuan earthquake does not belong to the deep plate boundary effect, but occurred in the brittle-ductile transition zone of the crust with a focal depth of 10 km-20 km, which is extremely destructive.
According to experts, there are earthquakes of magnitude 7 or above 18 times and earthquakes of magnitude 8 or above 1-2 times every year in the world. China is pushed by Indian plate and Pacific plate, and there are frequent earthquakes. Zhang Guomin said that from a big perspective, the Wenchuan earthquake is located in a large earthquake zone in China-the North-South seismic zone, and the central axis seismic zone is between 100 and 105, covering the areas from Ningxia to eastern Gansu, western Sichuan and Yunnan, belonging to the earthquake-intensive zone in China. To Xiaoli, Wenchuan is in the Longmenshan earthquake zone in Sichuan. Therefore, the probability of an earthquake here is very high.
According to Zhang Guomin, a researcher at the Institute of Earthquake Prediction, Seismological Bureau of China, Wenchuan Earthquake is an internal earthquake in Chinese mainland, which belongs to shallow earthquakes and has great destructive power. Zhang Guomin said that earthquakes can be divided into shallow earthquakes, moderate earthquakes and deep earthquakes according to focal depth. Most shallow earthquakes occurred at a depth of more than 30 kilometers below the surface, and the deepest earthquake could reach about 650 kilometers. Among them, shallow earthquakes has a high frequency, accounting for more than 70% of the total number of earthquakes, and the released seismic energy accounts for 85% of the total released energy. It is the main producer of earthquake disasters.