Online map of epicenter distribution of Wenchuan earthquake and aftershocks in China comes from the Wenchuan Earthquake Disaster Atlas, the scale of the map is 1:1000000, which is compiled by the Wenchuan Earthquake Disaster Atlas compilation committee, and published by Chengdu Map Publishing House.
The Wenchuan Earthquake Disaster Atlas is based on the work results of the expert group and closely focuses on the theme of "Wenchuan Earthquake Disaster". After the Wenchuan earthquake, the National Disaster Reduction Commission and the Ministry of Science and Technology jointly established an earthquake relief expert group, bringing together more than 30 ministries and commissions from the Ministry of Science and Technology, including the Ministry of Civil Affairs, the Ministry of Water Resources, the China Earthquake Administration, the State Bureau of Surveying and Mapping, and the Chinese Academy of Sciences. Experts and scholars have carried out multidisciplinary comprehensive research on the Wenchuan earthquake, obtained a large amount of monitoring information and evaluation data, and obtained fruitful research results.
Cause analysis of Wenchuan M8.0 earthquake
The Wenchuan earthquake occurred on the Longmenshan thrust nappe structural belt in Sichuan Province. The structural belt is the boundary structural belt between the Bayan Kara block of the Qinghai Tibet Plateau and the South China block of eastern China. It has experienced a long history of geological evolution and has a very complex structure and structure. The late Cenozoic tectonic deformation is mainly concentrated on the Anxian Guanxian (now Dujiangyan) fault (Qianshan fault), Beichuan Yingxiu fault (central fault) and Maoxian Wenchuan (Houshan fault) and their related folds. The 8.0 strong earthquake occurred on Beichuan Yingxiu fault, which was the result of the southeast pushing of Longmenshan thrust nappe and clockwise shear.
The power source of the Wenchuan earthquake and the southeast pushing of Longmen Mountain is the collision between the Indian plate and Eurasia and its northward pushing. The relative movement between the plates led to large-scale tectonic deformation in the Asian continent, resulting in the shortening of the crust, geomorphic uplift and eastward extrusion of the Qinghai Tibet Plateau. As the Qinghai Tibet Plateau was strongly blocked by the South China active block in the Sichuan Basin during its movement to the northeast, the stress was highly accumulated on the Longmenshan nappe structural belt, so that the dislocation occurred suddenly along the Beichuan Yingxiu fault, resulting in a strong earthquake of magnitude 8.0.
The focal mechanism solution of the Wenchuan M8.0 earthquake obtained by multiple research institutions shows that the southern section of the rupture surface of the earthquake is dominated by thrust and has a right-handed strike-slip component, and the northern section is dominated by right-handed strike-slip and has a thrust component. The rupture surface began to rupture from Wenchuan, the epicenter of the epicenter, and propagated in the direction of 49° east north at an average speed of 3.1 kilometers per second. The length of the rupture was about 300 kilometers. The total duration of the rupture process was nearly 120 seconds. The main energy of the earthquake was before. Released within 80 seconds, the maximum displacement is 9 meters, the focal depth is about 10 kilometers, the moment magnitude is 7.9, and the surface wave magnitude is 8.0.
Online map of historical earthquakes in Wenchuan disaster area in China
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