Lushan M_S7.0 earthquake:A special earthquake occurs on curved fault  

作　　者：ZHANG ZhuQi WANG WeiTao REN ZhiKun ZHANG PeiZhen FANG LiHua WU JianPing 

机构地区：[1]Institute of Geology,State Key Laboratory of Earthquake Dynamics,China Earthquake Administration [2]Institute of Geophysics,China Earthquake Administration

出　　处：《Chinese Science Bulletin》2013年第28期3483-3490,共8页

基　　金：supported by the Fundamental Research Funds for Central Public Welfare Research Institutes(DF-IGCEA-0608-2-18);the Special Fund for China Earthquake Research Project(201008003)

摘　　要：Relocation result shows that the aftershocks of the Lushan MS7.0 earthquake spatially distribute in a shape like"half bowl",indicating that the rupture structure of the mainshock is a highly curved surface.Kinematic analysis reveals that a laterally varied dislocation pattern occurs on this curved fault even though a single relative horizontal movement controls slip on this fault.Reverse slip prevails on curved fault.However,significant normal slip is predicted near the edge of north flank.Moreover,the north flank features left-lateral slip while the south flank contrarily features right-lateral slip.The relative scope of aftershock distribution implies inadequate breaking of the curved fault during the mainshock,calling for the attention to potential earthquake risk on the neighboring portions of the coseismic rupture due to significant increase of the coseismic Coulomb stress.Coseismic stress modeling also reveals that it is unnecessary for the stress on ruptured part to be unloaded following the earthquakes on the curved fault.The coseismic stress loading on ruptured elements unveils the specialty of faulting for the Lushan earthquake and we conclude that this specialty is due to the highly curved fault geometry.Relocation result shows that the aftershocks of the Lushan MS7.0 earthquake spatially distribute in a shape like ＂half bowl＂, indicating that the rupture structure of the mainshock is a highly curved surface. Kinematic analysis reveals that a laterally varied dislocation pattern occurs on this curved fault even though a single relative horizontal movement controls slip on this fault. Reverse slip prevails on curved fault. However, significant normal slip is predicted near the edge of north flank. Moreover, the north flank features left-lateral slip while the south flank contrarily features right-lateral slip. The relative scope of aftershock distribution implies inadequate breaking of the curved fault during the mainshock, calling for the attention to potential earthquake risk on the neighboring portions of the coseismic rupture due to significant increase of the coseismic Coulomb stress. Coseismic stress modeling also reveals that it is unnecessary for the stress on ruptured part to be unloaded following the earthquakes on the curved fault. The coseismic stress loading on ruptured elements unveils the specialty of faulting for the Lushan earthquake and we conclude that this specialty is due to the highly curved fault geometry.

关 键 词：弯曲故障 地震发生 庐山 地震空间分布 库仑应力 左旋走滑 地震断层 运动学分析 

分 类 号：P315[天文地球—地震学]