·14:00 on May 12, 2008: about 28 minutes.
·A strong earthquake of magnitude 8.0 in Wenchuan, Sichuan
·31 degrees north latitude, 103.4 east longitude Degree
·According to the report of the Ministry of Civil Affairs, as of 12:00 on the 3rd, more than 9,000 aftershocks had occurred. The Wenchuan earthquake in Sichuan has caused 90,560 deaths, 352,290 injuries, 26,221 missing people, and emergency relocation of 14,385,640 people. , a total of 45.509241 people were affected. As of 12:00 on the 24th, the government had received 26.101 billion yuan in donations from domestic and foreign countries, of which 17.147 billion yuan had actually been received, and 3.679 billion yuan had been allocated to the disaster areas. A total of 448,140 disaster relief tents, 35,458 simple houses (17,124 more than the previous day), 2,419,347 quilts, 3,304,526 pieces of clothing, 336,000 tons of fuel, and 723,000 tons of coal were transported to the disaster area. According to a report from the Ministry of Health, as of 12:00 on the 24th, a total of 75,086 people were hospitalized due to earthquake injuries, 40,644 people had been discharged, 3,484 people died in the hospital, 23,864 people were still hospitalized, 4,274 people were transferred from Sichuan to other provinces and cities for treatment, and a total of 289,457 injured people were treated. people. ·Economic losses reached more than 110.8 billion
The cause of the earthquake was the subduction of the Indian Plate to the Asian Plate, causing the Qinghai-Tibet Plateau to rise rapidly. The plateau material slowly flows eastward and is squeezed eastward along the Longmenshan tectonic belt on the eastern edge of the plateau. It encounters the strong obstruction of the rigid block beneath the Sichuan Basin, resulting in long-term accumulation of tectonic stress energy, and finally ends in the Beichuan-Yingxiu River in the Longmenshan Mountains. Areas are suddenly released. Thrust, right-lateral, and compression fault earthquakes. The seismogenic structure is the central fault zone of the Longmenshan tectonic belt. Under the action of compressive stress, it thrusts from south west to northeast. This earthquake is a unidirectional rupture earthquake and migrates from south west to northeast, causing aftershocks to the northeast. Expansion; After the mainshock of a compression-type thrust fault earthquake, the stress propagation and release process is relatively slow, which may result in aftershocks with greater intensity and longer duration. It is a shallow earthquake. The Wenchuan earthquake was not an effect of deep plate boundaries. It occurred in the brittle-ductile transition zone of the crust, with a focal depth of 10 kilometers to 20 kilometers, so it was extremely destructive.
Experts say that there are 18 earthquakes of magnitude 7 or above in the world every year, and 1-2 earthquakes of magnitude 8 or above. Our country is pushed by the Indian Plate and the Pacific Plate, and earthquake activities are relatively frequent. Zhang Guomin said that from a large perspective, the Wenchuan earthquake is located in a major seismic zone in my country - the north and south seismic zones. The central axis seismic zone in the central region is between 100 degrees and 105 degrees longitude, and the areas involved include Ningxia through Gansu The eastern part, western Sichuan, and Yunnan belong to the earthquake-intensive zone in my country. From a small perspective, Wenchuan is in the Longmenshan seismic zone of Sichuan. Therefore, the probability of earthquakes here is higher
According to Zhang Guomin, a researcher at the Earthquake Prediction Institute of the China Earthquake Administration, the earthquake in Wenchuan was an internal earthquake in mainland my country. It was a shallow earthquake and its destructive force was relatively large. . Zhang Guomin said that earthquakes can be divided into shallow source earthquakes, intermediate source earthquakes and deep source earthquakes according to the depth of the source. Most shallow earthquakes occur at a depth of more than 30 kilometers below the surface, while the deepest earthquakes can reach about 650 kilometers. Among them, shallow earthquakes have a high seismic frequency, accounting for more than 70% of the total number of earthquakes, and the seismic energy released accounts for 85% of the total released energy. They are the main creators of earthquake disasters3