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
文中基于D-InSAR技术,利用欧空局C波段升降轨哨兵SAR数据,获取了2021年5月22日青海玛多M_(W)7.3地震的InSAR同震形变场,并对同震形变的空间特征、量级和断层破裂的分段性进行了分析。哨兵卫星的高质量观测数据清晰地描绘了玛多地震的地...文中基于D-InSAR技术,利用欧空局C波段升降轨哨兵SAR数据,获取了2021年5月22日青海玛多M_(W)7.3地震的InSAR同震形变场,并对同震形变的空间特征、量级和断层破裂的分段性进行了分析。哨兵卫星的高质量观测数据清晰地描绘了玛多地震的地表破裂迹线,地表破裂长度约210km。为了进一步认识玛多地震断层深部的同震滑动分布特征和发震断层几何性质,基于升、降轨InSAR形变场及精定位余震数据确定的断层几何反演了同震滑动分布,并基于同震库仑应力变化分析了本次地震对周边区域的应力扰动。结果表明,玛多M_(W)7.3地震发生在巴颜喀拉块体内部的一条次级断层上,且与东昆仑断裂带的主断裂近平行,结合野外考察、地质资料和InSAR地表破裂迹线确定的发震断层为昆仑山口-江错断裂。玛多地震产生的同震形变场空间影响范围广,形变场的长轴呈NWW向,升、降轨观测的形变量符号相反,结合哨兵数据的观测几何确定发震断层的运动性质以左旋走滑为主。基于升、降轨InSAR数据得到的最大视线向(Line of Sight,LOS)形变量约为0.9m。同震滑动分布模型显示,整体上断层的走向为276°,倾角为80°,倾向NE,最大滑移量约为6m,平均滑动角为4°,矩震级为M_(W)7.45,地震主体破裂发生在0~10km深度范围内,同震破裂至地表,与野外考察所观测到的广泛分布的同震地表破裂带一致。以玛多-甘德断裂为接收断层的同震库仑应力模型显示,玛多地震在玛多-甘德断裂西段附近产生了明显的应力降,表明玛多地震释放了玛多-甘德断裂的库仑应力,导致后者的地震危险性可能大大降低;而在玛多-甘德断裂和昆仑山口-江错断裂交叉的区域存在应力加载效应,但考虑到玛多地震的余震会释放多余的能量,该区发生较大地震的危险性可能降低。以东昆仑断裂为接收断层的同震库仑应力模型显示,玛多地震在�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 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.
文摘文中基于D-InSAR技术,利用欧空局C波段升降轨哨兵SAR数据,获取了2021年5月22日青海玛多M_(W)7.3地震的InSAR同震形变场,并对同震形变的空间特征、量级和断层破裂的分段性进行了分析。哨兵卫星的高质量观测数据清晰地描绘了玛多地震的地表破裂迹线,地表破裂长度约210km。为了进一步认识玛多地震断层深部的同震滑动分布特征和发震断层几何性质,基于升、降轨InSAR形变场及精定位余震数据确定的断层几何反演了同震滑动分布,并基于同震库仑应力变化分析了本次地震对周边区域的应力扰动。结果表明,玛多M_(W)7.3地震发生在巴颜喀拉块体内部的一条次级断层上,且与东昆仑断裂带的主断裂近平行,结合野外考察、地质资料和InSAR地表破裂迹线确定的发震断层为昆仑山口-江错断裂。玛多地震产生的同震形变场空间影响范围广,形变场的长轴呈NWW向,升、降轨观测的形变量符号相反,结合哨兵数据的观测几何确定发震断层的运动性质以左旋走滑为主。基于升、降轨InSAR数据得到的最大视线向(Line of Sight,LOS)形变量约为0.9m。同震滑动分布模型显示,整体上断层的走向为276°,倾角为80°,倾向NE,最大滑移量约为6m,平均滑动角为4°,矩震级为M_(W)7.45,地震主体破裂发生在0~10km深度范围内,同震破裂至地表,与野外考察所观测到的广泛分布的同震地表破裂带一致。以玛多-甘德断裂为接收断层的同震库仑应力模型显示,玛多地震在玛多-甘德断裂西段附近产生了明显的应力降,表明玛多地震释放了玛多-甘德断裂的库仑应力,导致后者的地震危险性可能大大降低;而在玛多-甘德断裂和昆仑山口-江错断裂交叉的区域存在应力加载效应,但考虑到玛多地震的余震会释放多余的能量,该区发生较大地震的危险性可能降低。以东昆仑断裂为接收断层的同震库仑应力模型显示,玛多地震在�
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.
