On May 28, 2008 12 14: 28, an earthquake of magnitude 8 occurred in Wenchuan County, Sichuan Province. The epicentre is 3 1 N, 103.4 E, namely Yingxiu Town, Wenchuan County, with a focal depth of 20-30 kilometers, belonging to shallow earthquakes. The largest crack in this earthquake reached VII degree, and the particularly serious damage area exceeded 65,438+10,000 km2. According to the report of Seismological Bureau of China, 24,659 aftershocks have been detected in the main earthquake area.
The worst-hit areas are Beichuan, Shifang, Mianzhu, Yingxiu and Pengzhou. The earthquake felt a wide range, including Chongqing, Gansu, Shaanxi, Shanxi, Hubei, Beijing, Zhejiang, Shanghai, Jiangsu and other provinces (autonomous regions and municipalities).
(B) Wenchuan earthquake damage
Wenchuan earthquake and its secondary mountain disasters have caused great harm and destruction to villages and towns, road traffic, hydropower projects, ecological environment, water and soil resources and people's lives and property. As of July 2, 2008, 69 197 people were killed, 374 176 people were injured and 46.24 million people were affected. The earthquake caused great damage to the environment in the disaster area, causing serious damage to transportation and communication facilities, water conservancy and hydropower projects and agricultural and forestry land in the disaster area; The frequent occurrence of secondary disasters after the earthquake has greatly changed the original landform, causing river blockage, vegetation destruction and serious damage to human and natural landscapes.
1. Direct economic loss
The house was damaged. 23143,000 houses were damaged and 6.525 million houses collapsed, involving 3.379 million rural villagers and 0/53,200 urban residents. According to the preliminary assessment, the counties and some towns in Wenchuan, Beichuan and Qingchuan are basically in ruins.
2) Destroy infrastructure. Road traffic: Six expressways in Sichuan were partially damaged, and 10 national highway, provincial trunk highway, five national highways and 10 provincial highway were seriously damaged, and more than 2,300 kilometers of rural roads were basically damaged. Communication facilities: There are 3,897 disaster-stricken telecommunication offices in Sichuan, Gansu and Shaanxi provinces, 287 mobile communication and PHS base stations are damaged, 28,765 picometers of optical cables are damaged, and142,078 communication poles are broken, resulting in a direct economic loss of about 6.72 billion yuan. Water conservancy facilities: 2,380 reservoirs are in danger, including 69 dam-break hazards, 3 high-risk hazards 1 0, and 424 sub-high-risk hazards10. It is estimated that the cost of restoration and reconstruction is about 36 billion yuan. Power facilities: 764 hydropower stations were damaged. According to preliminary estimation, the direct economic loss of power grid exceeds 654.38+0.2 billion yuan. Agricultural production facilities: 49,949 rural water supply facilities were damaged, water supply pipelines were 3,6521km, and dams were damaged by 996.4km.
2. Indirect economic losses
1) Agricultural losses: The losses suffered by agricultural production and agricultural system in Sichuan are as high as 7.085 billion yuan. The affected area of crops is 980,000 mu, including 270,000 mu of grain crops and 7 1 10,000 mu of cash crops. The affected area of crops is 560,000 mu, and the harvest is 250,000 mu.
2) Industrial losses: A large number of enterprise workshops collapsed in the disaster area, and machinery, equipment, raw materials and inventory products were damaged. As of June 19, there were 48 12 enterprises in Sichuan province, including 674 enterprises with severe disasters, with economic losses of about 200 billion yuan. It will take at least three months for key large enterprises to resume normal production and operation.
3) Loss of service industry: There were138,960 damaged commercial outlets in the commercial circulation industry and service industry in the disaster area, with a loss of 26.782 billion yuan; Tourism, the earthquake caused 384 tourist attractions, 684 travel agencies, 524 star-rated hotels and 58 tourist car companies in Sichuan Province to close down, resulting in economic losses of 62.4 billion yuan; In May, the turnover of accommodation and catering enterprises above designated size in Sichuan Province was 7 1 100 million yuan, down 8.5% year-on-year.
4) Financial losses: 673 banking financial institutions in Sichuan Province closed down, including Agricultural Bank 155 and Rural Credit Cooperative 352. There are 80 branches, 570 branches, 869 marketing service departments, 2,489 houses with collapsed business premises and/kloc-0.28 million damaged houses, resulting in economic losses of about 369 million yuan.
(3) the cause of the earthquake
Wenchuan County is located in the western edge of Sichuan Basin, with Qionglai Mountain in the southwest, Longmen Mountain in the northeast and mountainous areas over 3,000 meters in the west. The ground elevation difference is large, the slope is steep, the valleys are vertical and horizontal, and the cutting is strong. The natural causes of the Wenchuan earthquake mainly include:
1) The Indian plate subducted into the Asian plate, causing the eastern edge of the Qinghai-Tibet Plateau to press eastward along the Longmenshan structural belt and meet the rigid block in the Sichuan Basin. The long-term accumulated structural stress energy was finally released suddenly in Beichuan-Yingxiu area of the Longmenshan structural belt.
2) The seismogenic structure is the central fault zone of Longmenshan structural belt. Under the action of compressive stress, it thrusts from southwest to northeast and migrates from southwest to northeast, resulting in the expansion of aftershocks in northeast. After the main earthquake, the process of stress propagation and release is slow, which leads to strong aftershocks and long duration.
3) Belongs to shallow earthquakes. 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 ~ 20km, which is extremely destructive.
4) There are also reasons for disasters: the terrain in the disaster area is complex, the mountain slope is large, and the height difference is large, which leads to a large number, large scale and serious secondary disasters such as collapses, landslides, mudslides and dammed lakes. As of September 4, 2008, Wenchuan earthquake has caused more than 2000 geological disasters/kloc-0, nearly 8700 potential hazards, and more than 30 dangerous dammed lakes such as Tangjiashan. At the same time, complex landforms and secondary disasters have also caused great difficulties for emergency rescue and disaster relief and post-disaster reconstruction. Man-made reasons: unreasonable urban and rural layout, low seismic strength of building structures, poor site conditions, etc.
(4) Disaster relief situation
Under the leadership of the CPC Central Committee, the State Council and the Central Military Commission, earthquake relief adheres to people-oriented, unified command and coordination, forming a strong joint force to overcome difficulties and give full play to the role of science and technology in disaster relief and post-disaster reconstruction.
By 18 12, the people who had been transferred had been rescued 1486405; 96,542 people were hospitalized due to earthquake injuries (excluding the number of patients in the disaster area), 92,533 people have been discharged and still hospitalized 1340 people, of which 552 people were still hospitalized for the wounded transferred from Sichuan to other provinces and cities, and 38 13 1433 people were treated by * *; Dispatch disaster relief tents1579,700, quilts 4,866,900, clothes141300, fuel 3.07 million tons and coal 6.556 million tons to the disaster area. 655,600 sets of transitional resettlement houses (prefabricated houses) have been installed, 3,800 sets are being installed and 600 sets are to be installed in earthquake-stricken areas, 900 sets have been shipped and 7,900 sets are to be shipped at the production site; Governments at all levels invested 66.749 billion yuan in earthquake relief. The central government invested 59.744 billion yuan, including 27.424 billion yuan for emergency rescue and disaster relief, and 32.32 billion yuan for post-disaster recovery and reconstruction. The local financial investment is 7.005 billion yuan; The national * * * received donations from all walks of life at home and abroad totaling 59.274 billion yuan, and actually received 59.26438+04 billion yuan, and has allocated donations totaling 23.823 billion yuan to the disaster-stricken areas; From the central reserve, 374,340 tons of disaster relief grain and 9,435 tons of edible oil were dispatched to the disaster-stricken areas. The total damaged mileage of telecommunication optical cable is 37,005 picokilometers, which has been restored to 3 1709 picokilometers. Sichuan, Gansu and Shaanxi affected commercial outlets (including individual industrial and commercial households) 138960, 127904 have resumed business; There are 1704 12 organized labor export and 664989 local jobs in the earthquake-stricken areas.
(V) Countermeasures and suggestions for post-disaster reconstruction
The restoration and reconstruction of earthquake-stricken areas is a complex and huge systematic project, involving ecology, resources, environment, society, economy and humanities, including road traffic, ecological environment, industrial layout, town location and other tasks. Therefore, according to the carrying capacity of local resources and environment, the post-disaster reconstruction plan should be made as soon as possible, and at the same time, long-term monitoring and forecasting of earthquakes and secondary mountain disasters and disaster prevention should be carried out, and basic research and the application of high technology should be strengthened.
1. Comprehensive evaluation of resources and environmental carrying capacity
Recovery and reconstruction after Wenchuan earthquake need to evaluate the suitability of reconstruction conditions in the planning area according to the natural geographical environment, geological conditions, disaster risk, population distribution and economic pattern, and combine the disaster situation, and comprehensively evaluate the carrying capacity of resources and environment in the planning area, so as to provide scientific basis for the overall layout of reconstruction planning and the location of towns, villages and enterprises.
Strengthen seismic zoning, carry out detailed engineering geological survey, and scientifically evaluate the seismic safety of the site.
2. Carry out monitoring, forecasting and disaster prevention of earthquakes and their secondary disasters.
First, deeply study the background, process, characteristics, causes and laws of earthquakes and their secondary disasters, delimit risk grade areas, and formulate disaster plans, prevention plans and plans; The second is to further improve the comprehensive measures to prevent earthquakes and their secondary disasters, strengthen the monitoring, prevention, prediction, early warning and evaluation of earthquakes and their secondary disasters, and revise and improve the disaster prevention plan.
3. Strengthen basic research and high-tech application.
Strengthen the research and application of the theory and technology of monitoring, forecasting and prevention of earthquakes and their secondary disasters, widely adopt "3S" technology, computer technology, network technology and modern communication technology, and improve the monitoring, forecasting, forecasting, early warning and rapid response system.