In the southern South-North Seismic Zone,China,seismic activity in the Yingjiang area of western Yunnan increased from December 2010,and eventually a destructive earthquake of Ms5.9 occurred near Yingjiang town on 10 ...In the southern South-North Seismic Zone,China,seismic activity in the Yingjiang area of western Yunnan increased from December 2010,and eventually a destructive earthquake of Ms5.9 occurred near Yingjiang town on 10 March 2011.The focal mechanism and hypocenter location of the mainshock suggest that the Dayingjiang Fault was the site of the mainshock rupture.However,most of foreshocks and all aftershocks recorded by a portable seismic array located close to the mainshock occurred along the N-S-striking Sudian Fault,indicating that this fault had an important influence on these shocks.Coulomb stress calculations show that three strong （magnitude ≥5.0） earthquakes that occurred in the study region in 2008 increased the coulomb stress along the plane parallel to the Dayingjiang Fault.This supports the Dayingjiang Fault,and not the Sudian Fault,as the seismogenic fault of the 2011 Ms5.9 Yingjiang earthquake.The strong earthquakes in 2008 also increased the Coulomb stress at depths of ≤5 km along the entire Sudian Fault,and by doing so increased the shallow seismic activity along the fault.This explains why the foreshocks and aftershocks of the 2011 Yingjiang earthquake were located mostly on the Sudian Fault where it cuts the shallow crust.The earthquakes at the intersection of the Sudian and Dayingjiang faults are distributed mainly along a belt that dips to the southeast at ～40°,suggesting that the Dayingjiang Fault in the mainshock area also dips to the southeast at ～40°.展开更多
前震序列分析在主震成核过程研究中具有重要意义。为探讨2011年3月10日盈江M_(S)5.8地震孕震发震机理,利用微震匹配定位技术(Match and Locate),以92个M_(S)≥2.0的地震事件作为模板事件,对主震区周围5个台站连续地震记录进行前震检测,...前震序列分析在主震成核过程研究中具有重要意义。为探讨2011年3月10日盈江M_(S)5.8地震孕震发震机理,利用微震匹配定位技术(Match and Locate),以92个M_(S)≥2.0的地震事件作为模板事件,对主震区周围5个台站连续地震记录进行前震检测,并结合前震、余震分布特点和主震前、后b值变化趋势等开展综合分析。结果显示,盈江M_(S)5.8地震前震主要集中于大盈江断裂第一分支西侧,余震沿ENE、SSE两个优势方向展布,推测此次盈江M_(S)5.8地震的主要动力学成因系印度板块的持续向东挤压致使ENE向的大盈江断裂和SSE向的隐伏断层构成的共轭断层系统发生破裂导致;主震前、后b值变化暗示腾冲火山区下方广泛存在的流体在此次地震孕育发生过程中起到重要的诱发和促进作用。展开更多
基金supported by the National Natural Science Foundation of China (NSFC-41174039)the China Geological Survey
文摘In the southern South-North Seismic Zone,China,seismic activity in the Yingjiang area of western Yunnan increased from December 2010,and eventually a destructive earthquake of Ms5.9 occurred near Yingjiang town on 10 March 2011.The focal mechanism and hypocenter location of the mainshock suggest that the Dayingjiang Fault was the site of the mainshock rupture.However,most of foreshocks and all aftershocks recorded by a portable seismic array located close to the mainshock occurred along the N-S-striking Sudian Fault,indicating that this fault had an important influence on these shocks.Coulomb stress calculations show that three strong （magnitude ≥5.0） earthquakes that occurred in the study region in 2008 increased the coulomb stress along the plane parallel to the Dayingjiang Fault.This supports the Dayingjiang Fault,and not the Sudian Fault,as the seismogenic fault of the 2011 Ms5.9 Yingjiang earthquake.The strong earthquakes in 2008 also increased the Coulomb stress at depths of ≤5 km along the entire Sudian Fault,and by doing so increased the shallow seismic activity along the fault.This explains why the foreshocks and aftershocks of the 2011 Yingjiang earthquake were located mostly on the Sudian Fault where it cuts the shallow crust.The earthquakes at the intersection of the Sudian and Dayingjiang faults are distributed mainly along a belt that dips to the southeast at ～40°,suggesting that the Dayingjiang Fault in the mainshock area also dips to the southeast at ～40°.
文摘前震序列分析在主震成核过程研究中具有重要意义。为探讨2011年3月10日盈江M_(S)5.8地震孕震发震机理,利用微震匹配定位技术(Match and Locate),以92个M_(S)≥2.0的地震事件作为模板事件,对主震区周围5个台站连续地震记录进行前震检测,并结合前震、余震分布特点和主震前、后b值变化趋势等开展综合分析。结果显示,盈江M_(S)5.8地震前震主要集中于大盈江断裂第一分支西侧,余震沿ENE、SSE两个优势方向展布,推测此次盈江M_(S)5.8地震的主要动力学成因系印度板块的持续向东挤压致使ENE向的大盈江断裂和SSE向的隐伏断层构成的共轭断层系统发生破裂导致;主震前、后b值变化暗示腾冲火山区下方广泛存在的流体在此次地震孕育发生过程中起到重要的诱发和促进作用。
