On May 12,2008,a magnitude 7.9 earthquake ruptured the Longmenshan fault system in Sichuan Province,China,collapsing buildings and killing tens of thousands people.As predicted,aftershocks may last for at least one ye...On May 12,2008,a magnitude 7.9 earthquake ruptured the Longmenshan fault system in Sichuan Province,China,collapsing buildings and killing tens of thousands people.As predicted,aftershocks may last for at least one year,and moreover,large aftershocks are likely to occur.Therefore,it is critical to outline the areas with potential aftershocks before reconstruction and resettling people as to avoid future disasters.It is demonstrated that the redistribution of stress induced by an earthquake should trigger successive seismic activity.Based on static stress triggering theory,we calculated the coseismic stress changes on major faults induced by the Wenchuan earthquake,with elastic dislocation the-ory and the multilayered crustal model.We also discuss the stress distribution and its significance for future seismic activity under the impact of the Wenchuan earthquake.It is shown that coulomb failure stress(CFS) increases obviously on the Daofu-Kangding segment of the Xianshuihe Fault,the Maqu and Nanping segment of the Eastern Kunlun Fault,the Qingchuan Fault,southern segment of the Min-jiang Fault,Pengxian-Guanxian Fault,Jiangyou-Guangyuan Fault,and Jiangyou-Guanxian Fault.The increased stress raises the probability of earthquake occurrence on these faults.Since these areas are highly populated,earthquake monitoring and early disaster alarm system are needed.CFS increases with a magnitude of 0.03―0.06 MPa on the Qingchuan Fault,which is close to the northern end of the rapture of Wenchuan earthquake.The occurrence of some strong aftershocks,including three events with magnitude higher than 5.0,indicates that the seismic activities have been triggered by the main shock.Aftershocks seem to migrate northwards.Since the CFS change on the Lueyang-Mianxian Fault located on the NEE of the Qingchuan Fault is rather small(±0.01 MPa),the migration of aftershocks might be terminated in the area near Hanzhong City.The CFS change on the western Qinling Fault is around 10 Pa,and the impact of static triggering can be neglected.T展开更多
On April 20, 2013, an Ms7.0 earthquake occurred in Ya'an-Lushan region, Sichuan Province, China, killing and injuring morethan one thousand people. Therefore, it is critical to outline the areas with potential aft...On April 20, 2013, an Ms7.0 earthquake occurred in Ya'an-Lushan region, Sichuan Province, China, killing and injuring morethan one thousand people. Therefore, it is critical to outline the areas with potential aftershocks before reconstruction andre-settlement as to avoid future disasters. Based on the elastic dislocation theory and multi-layered lithospheric model, we calculate the co-and post-seismic stress changes caused by the Wenchuan and Lushan earthquakes to discuss the relationshipbetween Mw7.9 Wenchuan earthquake and Ms7.0 Lushan earthquake, the influences on the distribution of aftershock caused bythe Lushan earthquake, and the stress changes on major faults in this region. It is shown that the Coulomb failure stress increment on the hypocenter of Lushan earthquake caused by the Wenchuan earthquake is about 0.0037-0.0113 MPa. And the possible maximum value (0.0113 MPa) is larger than the threshold of stress triggering. Therefore, the occurrence of Lushanearthquake is probably effectively promoted by the Wenchuan earthquake. The aftershock distribution is well explained by theco-seismic stress changes of Lushan earthquake. By the two ends of the rupture of Lushan earthquake with increased Coulombfailure stress, a lack of aftershock recordings indicates the high seismic hazard. The stress accumulation and correspondingseismic hazard on the Kangding-Dafu segment of the Xinshuihe fault, the Beichuan-Yingxiu fault, the Pengxian-Guanxianfault, and the Ya'an fault are further increased by the Lushan earthquake and post-seismic process of Wenchuan earthquake.展开更多
On August 8, 2017, a M7.0 earthquake occurred in Jiuzhaigou County, Sichuan Province, China, resulting in significant casualties and property damage. Therefore, it is critical to identify the areas of potential afters...On August 8, 2017, a M7.0 earthquake occurred in Jiuzhaigou County, Sichuan Province, China, resulting in significant casualties and property damage. Therefore, it is critical to identify the areas of potential aftershocks before reconstruction and re-settling people to avoid future disasters. Based on the elastic dislocation theory and a multi-layered lithospheric model, we calculate the Coulomb failure stress changes caused by the Wenchuan and Jiuzhaigou earthquakes, discuss the relationship between the Mw7.9 Wenchuan and M7.0 Jiuzhaigou earthquakes, and analyze the influence of the aftershock distribution and stress changes on the major faults in this region caused by the Jiuzhaigou earthquake. The co-and post-seismic stress changes caused by the Wenchuan earthquake significantly increased the stress accumulation at the hypocenter of the Jiuzhaigou earthquake. Therefore,the occurrence of the Jiuzhaigou earthquake was probably stimulated by the Wenchuan earthquake. The aftershock distribution is well explained by the co-seismic stress changes of the Jiuzhaigou earthquake. The stress accumulation and corresponding seismic hazard on the Maqu-Heye segment of the East Kunlun fault and the northern extremity of the Huya fault has been further increased by the Jiuzhaigou earthquake.展开更多
Coulomb failure stress changes (ΔCFS) are used in the study of reservoir-induced seismicity (RIS) generation.The threshold value of ΔCFS that can trigger earthquakes is an important issue that deserves thorough rese...Coulomb failure stress changes (ΔCFS) are used in the study of reservoir-induced seismicity (RIS) generation.The threshold value of ΔCFS that can trigger earthquakes is an important issue that deserves thorough research.The M s 6.1 earthquake in the Xinfengjiang Reservoir in 1962 is well acknowledged as the largest reservoir-induced earthquake in China.Therefore, it is a logical site for quantitative calculation of ΔCFS induced by the filling of the reservoir and for investigating the magnitude of CFS that can trigger reservoir seismic activities.To better understand the RIS mechanism, a three-dimensional poroelastic finite element model of the Xinfengjiang Reservoir is proposed here, taking into consideration of the precise topography and dynamic water level.We calculate the instant changes of stress and pore pressure induced by water load, and the time variation of effective stresses due to pore water diffusion.The CFS on the seismogenesis faults and the accumulation of strain energy in the reservoir region are also calculated.Primary results suggest that the reservoir impoundment increases both pore pressure and CFS on the fault at the focal depth.The diffusion of pore pressure was likely the main factor that triggered the main earthquake, whereas the elastic stress owing to water load was relatively small.The magnitude of CFS on seismogenesis fault can reach approximately 10 kPa, and the ΔCFS values at the hypocenter can be about 0.7-3.0 kPa, depending on the fault diffusion coefficient.The calculated maximum vertical subsidence caused by the water load in the Xinfengjiang Reservoir is 17.5 mm, which is in good agreement with the observed value of 15 mm.The accumulated strain energy owing to water load was only about 7.3×10 11 J, even less than 1% of the seismic wave energy released by the earthquake.The reservoir impoundment was the only factor that triggered the earthquake.展开更多
基金Supported by Knowledge Innovation Program of Chinese Academy of Sciences (Grant No. KZCX-SW-153)National Natural Science Foundation of China (Grant Nos. 40574011 and 40474028)
文摘On May 12,2008,a magnitude 7.9 earthquake ruptured the Longmenshan fault system in Sichuan Province,China,collapsing buildings and killing tens of thousands people.As predicted,aftershocks may last for at least one year,and moreover,large aftershocks are likely to occur.Therefore,it is critical to outline the areas with potential aftershocks before reconstruction and resettling people as to avoid future disasters.It is demonstrated that the redistribution of stress induced by an earthquake should trigger successive seismic activity.Based on static stress triggering theory,we calculated the coseismic stress changes on major faults induced by the Wenchuan earthquake,with elastic dislocation the-ory and the multilayered crustal model.We also discuss the stress distribution and its significance for future seismic activity under the impact of the Wenchuan earthquake.It is shown that coulomb failure stress(CFS) increases obviously on the Daofu-Kangding segment of the Xianshuihe Fault,the Maqu and Nanping segment of the Eastern Kunlun Fault,the Qingchuan Fault,southern segment of the Min-jiang Fault,Pengxian-Guanxian Fault,Jiangyou-Guangyuan Fault,and Jiangyou-Guanxian Fault.The increased stress raises the probability of earthquake occurrence on these faults.Since these areas are highly populated,earthquake monitoring and early disaster alarm system are needed.CFS increases with a magnitude of 0.03―0.06 MPa on the Qingchuan Fault,which is close to the northern end of the rapture of Wenchuan earthquake.The occurrence of some strong aftershocks,including three events with magnitude higher than 5.0,indicates that the seismic activities have been triggered by the main shock.Aftershocks seem to migrate northwards.Since the CFS change on the Lueyang-Mianxian Fault located on the NEE of the Qingchuan Fault is rather small(±0.01 MPa),the migration of aftershocks might be terminated in the area near Hanzhong City.The CFS change on the western Qinling Fault is around 10 Pa,and the impact of static triggering can be neglected.T
基金supported by National Natural Science Foundation of China (Grant Nos.41074052,41204067,41174086 and 41021003)Special Project Seismic Commonwealth Research (Grant No.201308013)Key Development Program of Chinese Academy of Sciences (Grant No.KZZD-EW-TZ-05)
文摘On April 20, 2013, an Ms7.0 earthquake occurred in Ya'an-Lushan region, Sichuan Province, China, killing and injuring morethan one thousand people. Therefore, it is critical to outline the areas with potential aftershocks before reconstruction andre-settlement as to avoid future disasters. Based on the elastic dislocation theory and multi-layered lithospheric model, we calculate the co-and post-seismic stress changes caused by the Wenchuan and Lushan earthquakes to discuss the relationshipbetween Mw7.9 Wenchuan earthquake and Ms7.0 Lushan earthquake, the influences on the distribution of aftershock caused bythe Lushan earthquake, and the stress changes on major faults in this region. It is shown that the Coulomb failure stress increment on the hypocenter of Lushan earthquake caused by the Wenchuan earthquake is about 0.0037-0.0113 MPa. And the possible maximum value (0.0113 MPa) is larger than the threshold of stress triggering. Therefore, the occurrence of Lushanearthquake is probably effectively promoted by the Wenchuan earthquake. The aftershock distribution is well explained by theco-seismic stress changes of Lushan earthquake. By the two ends of the rupture of Lushan earthquake with increased Coulombfailure stress, a lack of aftershock recordings indicates the high seismic hazard. The stress accumulation and correspondingseismic hazard on the Kangding-Dafu segment of the Xinshuihe fault, the Beichuan-Yingxiu fault, the Pengxian-Guanxianfault, and the Ya'an fault are further increased by the Lushan earthquake and post-seismic process of Wenchuan earthquake.
基金supported by the National Natural Science Foundation of China(Grant Nos.41674106 and 41541034)
文摘On August 8, 2017, a M7.0 earthquake occurred in Jiuzhaigou County, Sichuan Province, China, resulting in significant casualties and property damage. Therefore, it is critical to identify the areas of potential aftershocks before reconstruction and re-settling people to avoid future disasters. Based on the elastic dislocation theory and a multi-layered lithospheric model, we calculate the Coulomb failure stress changes caused by the Wenchuan and Jiuzhaigou earthquakes, discuss the relationship between the Mw7.9 Wenchuan and M7.0 Jiuzhaigou earthquakes, and analyze the influence of the aftershock distribution and stress changes on the major faults in this region caused by the Jiuzhaigou earthquake. The co-and post-seismic stress changes caused by the Wenchuan earthquake significantly increased the stress accumulation at the hypocenter of the Jiuzhaigou earthquake. Therefore,the occurrence of the Jiuzhaigou earthquake was probably stimulated by the Wenchuan earthquake. The aftershock distribution is well explained by the co-seismic stress changes of the Jiuzhaigou earthquake. The stress accumulation and corresponding seismic hazard on the Maqu-Heye segment of the East Kunlun fault and the northern extremity of the Huya fault has been further increased by the Jiuzhaigou earthquake.
基金supported by Key Laboratory of Earthquake DynamicsSinoProbe-07 Project of the Ministry of Land and Resources+1 种基金National Basic Research Program of China(Grant No.2008CB425701)National High-tech R&D Program of China(Grant No.2010AA012402)
文摘Coulomb failure stress changes (ΔCFS) are used in the study of reservoir-induced seismicity (RIS) generation.The threshold value of ΔCFS that can trigger earthquakes is an important issue that deserves thorough research.The M s 6.1 earthquake in the Xinfengjiang Reservoir in 1962 is well acknowledged as the largest reservoir-induced earthquake in China.Therefore, it is a logical site for quantitative calculation of ΔCFS induced by the filling of the reservoir and for investigating the magnitude of CFS that can trigger reservoir seismic activities.To better understand the RIS mechanism, a three-dimensional poroelastic finite element model of the Xinfengjiang Reservoir is proposed here, taking into consideration of the precise topography and dynamic water level.We calculate the instant changes of stress and pore pressure induced by water load, and the time variation of effective stresses due to pore water diffusion.The CFS on the seismogenesis faults and the accumulation of strain energy in the reservoir region are also calculated.Primary results suggest that the reservoir impoundment increases both pore pressure and CFS on the fault at the focal depth.The diffusion of pore pressure was likely the main factor that triggered the main earthquake, whereas the elastic stress owing to water load was relatively small.The magnitude of CFS on seismogenesis fault can reach approximately 10 kPa, and the ΔCFS values at the hypocenter can be about 0.7-3.0 kPa, depending on the fault diffusion coefficient.The calculated maximum vertical subsidence caused by the water load in the Xinfengjiang Reservoir is 17.5 mm, which is in good agreement with the observed value of 15 mm.The accumulated strain energy owing to water load was only about 7.3×10 11 J, even less than 1% of the seismic wave energy released by the earthquake.The reservoir impoundment was the only factor that triggered the earthquake.
