Because of the confining compression of the Pacific, Eurasian and Indian plates, the Chinese mainland is frequently stricken with earthquakes, especially in the Qinghai Tibet Plateau and surrounding areas and along th...Because of the confining compression of the Pacific, Eurasian and Indian plates, the Chinese mainland is frequently stricken with earthquakes, especially in the Qinghai Tibet Plateau and surrounding areas and along the NS-trending tectonic zone from Yinchuan to Lanzhou, Chengdu, and finally to the Kunming tectonic belt （Fig. 1）. Historical records show that there are 14 earthquakes of 〉Ms 8 occurring in the two regions, eight of which occurred along the latter tectonic belt. The 2008 Wenchuan earthquake located on both the NS tectonic zone and the Longmenshan fault zone along the eastern margin of the Qinghai-Tibet Plateau.展开更多
Longmen Shan is located the special joint be-tween Tibetan Plateau inland in the west and Yangtze craton in the east. Consisting of a se-ries of parallel imbricated thrust, it develops, from the west to the east, the ...Longmen Shan is located the special joint be-tween Tibetan Plateau inland in the west and Yangtze craton in the east. Consisting of a se-ries of parallel imbricated thrust, it develops, from the west to the east, the Maoxian- Wenchuan, Beichuan-Yingxiu and Pengxian- ﹡This research was supported by China National Natural Science Foundation grant 40841010, 40972083 and China National Science and Technology supporting Plan Foundation grant 2006BAC13B02-07, 2006BAC13B01-604. Guanxian faults. The Wenchuan earthquake is a thrust with strike-slip type, and thre surface ruptures are located on the Beichuan-Yingxiu fault zone and Pengxian-Guanxian fault zone. The surface rupture on the Beichuan-Yingxiu fault shows the thrust and dextral slip charac-teristic. The maximum vertical displacement of the surface rupture is about 10.3 m and the maxi-mum right-lateral displacement is about 5.85m. Though the vertical displacements and the hori-zontal displacements in the different segments have certain differences, as a whole, the ratio of the vertical displacement and the horizontal dis-placement is close to 1:1. The surface rupture on the Pengxian-Guanxian fault shows thrust and dextral characteristic. The rates of vertical dis-placements and the horizontal displacements ones on the most other segments are between 1:3 and 1:2. So the Beichuan- Yingxiu fault is a dextral-slip and thrust fault and the average ver-tical displacement is equal to the average hori-zontal displacement, while the Pengxian- Guan xian fault is thrust fault with a little dextral-slip component. The total intensity area above Ⅵ de-gree of the Wenchuan earthquake is about 333000 km2. The high earthquake intensity line stretches to N40-50°E along Longmen Shan tectonic belt. The rate of the long axis and the minor is betw- een 8:1 and 10:1. Three Ⅺ intensity regions are isolated in distribution. It presents a multipoint instantaneous characteristic of the rupture.展开更多
Longmen Shan is located the special joint between the Qinghai-Tibetan Plateau in the west and the Yangtze craton in the east. Consisting of a series of parallel imbricated thrust, it develops, from the west to the eas...Longmen Shan is located the special joint between the Qinghai-Tibetan Plateau in the west and the Yangtze craton in the east. Consisting of a series of parallel imbricated thrust, it develops, from the west to the east, the Maoxian-Wenchuan, Yingxiu-Beichuan and Pengxian-Guanxian faults. Wenchuan Ms 8.0 earthquake is a thrust with strike-slip type, and surface ruptures are located in Yingxiu-Beichuan fault zone and Peng- xian-Guanxian fault zone. Based on the geological background, tectonic setting, the active tectonics of Long- men Shan and surface ruptures of the Wenchuan earthquake, a dynamical model to illustrate possible links between surface processes and upward extrusion of lower crustal flow channel at the eastern margin of the Tibetan plateau have been studied, and the results is the material in lower crust in the Longmen Shan moving as nearly-vertical extrusion and uplift, resulting in the surface rate of tectonic movement differing according to depth rate as well as the occurrence of large shallow Wenchuan earthquake.展开更多
Based on the data of mobile gravity observation from 1998 to 2008 in western Sichuan, spatial dynamic variation results of regional gravity field are obtained. The relationship between the gravity variation features a...Based on the data of mobile gravity observation from 1998 to 2008 in western Sichuan, spatial dynamic variation results of regional gravity field are obtained. The relationship between the gravity variation features and Wenchuan Ms8.0 earthquake is systematically analyzed. The results show： 1 ） Gravity variation is closely related to active fault tectonics, and gravity measurement can better reflect material migration following crustal tectonic activity near active fault. 2）The gravity field appeared a wider range regional gravity variation during Wenchuan earthquake occurrence. The dynamic patterns of gravity field demonstrates the evolution process of gravity field ： quasi - homogeneous state non - homogeneous state-earthquake occurrence.展开更多
The Wenchuan earthquake coseismic deformation field is inferred from the coseismic dislocation data based on a 3-D geometric model of the active faults in Sichuan-Yunnan region. Then the potential dislocation displace...The Wenchuan earthquake coseismic deformation field is inferred from the coseismic dislocation data based on a 3-D geometric model of the active faults in Sichuan-Yunnan region. Then the potential dislocation displacement is inverted from the deformation field in the 3-D geometric model. While the faults＇ slip velocities are inverted from GPS and leveling data, which can be used as the long-term slip vector. After the potential dislocation displacements are projected to long-term slip direction, we have got the influence of Wenchuan earthquake on active faults in Sichuan-Yunnan region. The results show that the northwestern segment of Longmenshan fault, the southern segments of Xianshuihe fault, Anninghe fault, Zemuhe fault, northern and southern segments of Daliangshan fault, Mabian fault got earthquake risks advanced of 305, 19, 12, 9.1 and 18, 51 years respectively in the eastern part of Sichuan and Yunnan. The Lijiang-Xiaojinhe fault, Nujiang fault, Longling-Lancang fault, Nantinghe fault and Zhongdian fault also got earthquake risks advanced in the western part of Sichuan-Yunnan region. Whereas the northwestern segment of Xianshuihe fault and Xiaojiang fault got earthquake risks reduced after the Wenchuan earthquake.展开更多
Based on the lateral segmentation and vertical stratification characteristics of the crustal medium in Sichuan-Yunnan region,and the asymmetry of the static dislocations on the coseismic fault plane of the Wenchuan M_...Based on the lateral segmentation and vertical stratification characteristics of the crustal medium in Sichuan-Yunnan region,and the asymmetry of the static dislocations on the coseismic fault plane of the Wenchuan M_S8.0 earthquake,we built a three-dimensional viscoelastic finite element model of the crust in the Sichuan-Yunnan region.The postseismic impact of the Wenchuan M_S8.0 earthquake on the Sichuan-Yunnan region was studied.The results show that:①The far-field horizontal deformation caused by the viscoelastic relaxation of the medium in the 10 years after the earthquake is about 0-20 mm within the Sichuan-Yunnan diamond-shaped block,which has a greater influence on north side and smaller on south side.②In the 10 years after the earthquake,the far-field vertical deformation caused by the viscoelastic relaxation effect of the medium is small,and it shows an increase of about 0-4 mm in most areas of the Sichuan-Yunnan diamond-shaped block.③The Xianshuihe fault and the eastern segment of the East Kunlun fault,which are close to the seismogenic fault,show a high gradient on deformation fields after the earthquake.④In order to compare with the strong earthquake activity in the SichuanYunnan region after the Wenchuan earthquake,the horizontal stress state and the Coulomb failure stress change of the active block boundary are also calculated.From the spatial distribution of the coseismic and postseismic displacement field,the fault activity characteristics reflected by the stress state and the stress loading of the fault layer reflected by the Coulomb failure stress change,there is a certain correlation with the spatial distribution of strong earthquake activity in this region.展开更多
文摘Because of the confining compression of the Pacific, Eurasian and Indian plates, the Chinese mainland is frequently stricken with earthquakes, especially in the Qinghai Tibet Plateau and surrounding areas and along the NS-trending tectonic zone from Yinchuan to Lanzhou, Chengdu, and finally to the Kunming tectonic belt （Fig. 1）. Historical records show that there are 14 earthquakes of 〉Ms 8 occurring in the two regions, eight of which occurred along the latter tectonic belt. The 2008 Wenchuan earthquake located on both the NS tectonic zone and the Longmenshan fault zone along the eastern margin of the Qinghai-Tibet Plateau.
文摘Longmen Shan is located the special joint be-tween Tibetan Plateau inland in the west and Yangtze craton in the east. Consisting of a se-ries of parallel imbricated thrust, it develops, from the west to the east, the Maoxian- Wenchuan, Beichuan-Yingxiu and Pengxian- ﹡This research was supported by China National Natural Science Foundation grant 40841010, 40972083 and China National Science and Technology supporting Plan Foundation grant 2006BAC13B02-07, 2006BAC13B01-604. Guanxian faults. The Wenchuan earthquake is a thrust with strike-slip type, and thre surface ruptures are located on the Beichuan-Yingxiu fault zone and Pengxian-Guanxian fault zone. The surface rupture on the Beichuan-Yingxiu fault shows the thrust and dextral slip charac-teristic. The maximum vertical displacement of the surface rupture is about 10.3 m and the maxi-mum right-lateral displacement is about 5.85m. Though the vertical displacements and the hori-zontal displacements in the different segments have certain differences, as a whole, the ratio of the vertical displacement and the horizontal dis-placement is close to 1:1. The surface rupture on the Pengxian-Guanxian fault shows thrust and dextral characteristic. The rates of vertical dis-placements and the horizontal displacements ones on the most other segments are between 1:3 and 1:2. So the Beichuan- Yingxiu fault is a dextral-slip and thrust fault and the average ver-tical displacement is equal to the average hori-zontal displacement, while the Pengxian- Guan xian fault is thrust fault with a little dextral-slip component. The total intensity area above Ⅵ de-gree of the Wenchuan earthquake is about 333000 km2. The high earthquake intensity line stretches to N40-50°E along Longmen Shan tectonic belt. The rate of the long axis and the minor is betw- een 8:1 and 10:1. Three Ⅺ intensity regions are isolated in distribution. It presents a multipoint instantaneous characteristic of the rupture.
文摘Longmen Shan is located the special joint between the Qinghai-Tibetan Plateau in the west and the Yangtze craton in the east. Consisting of a series of parallel imbricated thrust, it develops, from the west to the east, the Maoxian-Wenchuan, Yingxiu-Beichuan and Pengxian-Guanxian faults. Wenchuan Ms 8.0 earthquake is a thrust with strike-slip type, and surface ruptures are located in Yingxiu-Beichuan fault zone and Peng- xian-Guanxian fault zone. Based on the geological background, tectonic setting, the active tectonics of Long- men Shan and surface ruptures of the Wenchuan earthquake, a dynamical model to illustrate possible links between surface processes and upward extrusion of lower crustal flow channel at the eastern margin of the Tibetan plateau have been studied, and the results is the material in lower crust in the Longmen Shan moving as nearly-vertical extrusion and uplift, resulting in the surface rate of tectonic movement differing according to depth rate as well as the occurrence of large shallow Wenchuan earthquake.
基金supported by the National Natural Science Foundation(40874035)a special earthquake research project grant from China Earthquake Administration(200908029)
文摘Based on the data of mobile gravity observation from 1998 to 2008 in western Sichuan, spatial dynamic variation results of regional gravity field are obtained. The relationship between the gravity variation features and Wenchuan Ms8.0 earthquake is systematically analyzed. The results show： 1 ） Gravity variation is closely related to active fault tectonics, and gravity measurement can better reflect material migration following crustal tectonic activity near active fault. 2）The gravity field appeared a wider range regional gravity variation during Wenchuan earthquake occurrence. The dynamic patterns of gravity field demonstrates the evolution process of gravity field ： quasi - homogeneous state non - homogeneous state-earthquake occurrence.
基金supported by the Key Project of Chinese Programs for Fundamental Research and Development (2004CB418406)
文摘The Wenchuan earthquake coseismic deformation field is inferred from the coseismic dislocation data based on a 3-D geometric model of the active faults in Sichuan-Yunnan region. Then the potential dislocation displacement is inverted from the deformation field in the 3-D geometric model. While the faults＇ slip velocities are inverted from GPS and leveling data, which can be used as the long-term slip vector. After the potential dislocation displacements are projected to long-term slip direction, we have got the influence of Wenchuan earthquake on active faults in Sichuan-Yunnan region. The results show that the northwestern segment of Longmenshan fault, the southern segments of Xianshuihe fault, Anninghe fault, Zemuhe fault, northern and southern segments of Daliangshan fault, Mabian fault got earthquake risks advanced of 305, 19, 12, 9.1 and 18, 51 years respectively in the eastern part of Sichuan and Yunnan. The Lijiang-Xiaojinhe fault, Nujiang fault, Longling-Lancang fault, Nantinghe fault and Zhongdian fault also got earthquake risks advanced in the western part of Sichuan-Yunnan region. Whereas the northwestern segment of Xianshuihe fault and Xiaojiang fault got earthquake risks reduced after the Wenchuan earthquake.
基金the Seismological Science and Technology Spark Program of the China Earthquake Administration，“A Study of the Impacts and Observations of the Wenchuan Earthquake on the Post-earthquake in the Sichuan-Yunnan Region”(XH16058Y)the Youth Earthquake Tracking Project of the China Earthquake Administration Monitoring and Forecasting Division(2017010219)
文摘Based on the lateral segmentation and vertical stratification characteristics of the crustal medium in Sichuan-Yunnan region,and the asymmetry of the static dislocations on the coseismic fault plane of the Wenchuan M_S8.0 earthquake,we built a three-dimensional viscoelastic finite element model of the crust in the Sichuan-Yunnan region.The postseismic impact of the Wenchuan M_S8.0 earthquake on the Sichuan-Yunnan region was studied.The results show that:①The far-field horizontal deformation caused by the viscoelastic relaxation of the medium in the 10 years after the earthquake is about 0-20 mm within the Sichuan-Yunnan diamond-shaped block,which has a greater influence on north side and smaller on south side.②In the 10 years after the earthquake,the far-field vertical deformation caused by the viscoelastic relaxation effect of the medium is small,and it shows an increase of about 0-4 mm in most areas of the Sichuan-Yunnan diamond-shaped block.③The Xianshuihe fault and the eastern segment of the East Kunlun fault,which are close to the seismogenic fault,show a high gradient on deformation fields after the earthquake.④In order to compare with the strong earthquake activity in the SichuanYunnan region after the Wenchuan earthquake,the horizontal stress state and the Coulomb failure stress change of the active block boundary are also calculated.From the spatial distribution of the coseismic and postseismic displacement field,the fault activity characteristics reflected by the stress state and the stress loading of the fault layer reflected by the Coulomb failure stress change,there is a certain correlation with the spatial distribution of strong earthquake activity in this region.
