2014年云南鲁甸M_S6.5地震震源运动学特征  

THE KINEMATIC CHARACTERISTICS OF THE M_S6.5 LUDIAN YUNNAN EARTHQUAKE IN 2014

作　　者：赵旭[1,2] 刘杰[2] 冯蔚[2] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国地震台网中心,北京100045

出　　处：《地震地质》2014年第4期1157-1172,共16页Seismology and Geology

基　　金：国家海洋局行业科研专项(201405026);中国地震局"云南鲁甸6.5级地震专题研究"项目共同资助

摘　　要：使用中国数字地震台网记录的区域宽频带波形,通过频率域和时间域多步反演,研究了2014年云南鲁甸MS6.5地震震源运动学特征.基于点源的震源机制解揭示：地震发震断层面参数分别为走向342°/倾角83°/滑动角-34°,表现为一次左旋走滑型为主兼有少量正断倾滑分量的事件.质心在水平方向位于震中（103.354°E,27.109°N）东南约5.4km,最佳波形拟合的质心深度约4.4km,平均总标量地震矩M0为2.1×1018N·m,矩震级MW约6.1.破裂过程图像显示：此地震为一次不对称双侧破裂事件,破裂半径约10km,整个破裂面积为227.6km2,平均滑动量约0.16m.破裂在6s内释放了大多数能量,震后0～2s,破裂以孕震点为中心向NW和SE两侧同时扩展,2s后,破裂表现出明显的方向性,主要向SE（沿走向342°相反方向）扩展,故导致SE向多数台站视破裂持续时间总体偏小,最小值为2s.约6s后破裂基本趋于停止.推断鲁甸地震破裂在上地壳浅层集中释放了大多数能量是导致灾害严重的主要原因之一.We employ multistep inversions in the frequency or time domain to infer the kinematic characteristics of the MS6.5 Ludian,Yunnan earthquake in 2014,mainly using regional broadband waves recorded by the China Digital Seismic Network.In this paper,we firstly invert the focal mechanism solution and the centroid depth of the Ludian earthquake,and then determine the bestfitting finite-fault model and the dominant rupture direction.According to the above results,we further analyze and discuss the kinematic characteristics of the Ludian earthquake,and explore preliminarily the reason for the serious disaster caused by this event.We take into account some factors which could have effects on the inversion results,e.g.the use of different waves and simplified 1-D velocity models.Several test results indicate that the misfit between observed waves and synthetics is better,if we use the full waves and the 1-D velocity model （Model M2） in this study area.According to the point-source model （focal mechanism solution）,this event occurs on a true rupture plane （strike =342°,dip =83°,and rake =-34°）,which shows a leftlateral strike-slip faulting with a minor normal oblique component.The centroid in the horizontal direction is located at nearly 5.4km southeast of the epicenter （27.109°N/103.354°E）,and the bestfitting centroid depth is around 4.4km.The total scalar moment,M0,is retrieved with an average value of 2.1×1018N · m（or moment magnitude Mw6.1）.The rupture history indicates the event can be considered to have an asymmetric bilateral rupture source with a radius of 10km.The total rupture area is about 227.6km2 with an average slip of nearly 0.16m.Most of the energy releases within about 6s.From 0s to 2s,the energetic rupture starts at the nucleation center,then propagates bilaterally along the fault plane.After 2s,the rupture mainly extends south-east,showing an obvious rupture directivity.Finally,the rupture ends at nearly 6s.In order to investigate rupture directivity of the Ludian earthquake,we

关 键 词：云南鲁甸地震 Eikonal震源模型 震源机制解 破裂过程 

分 类 号：P315.2[天文地球—地震学]