菏泽5．9级地震的发震构造及其前兆构造活动

SEISMOGENETIC STRUCTURE AND PRECURSOR TECTONIC ACTIVITY OF HEZE EARTHQUAKE

在分析了地震地质、物探、卫片等新的资料的基础上，认为在菏泽地震区地下隐伏着一条北东向深大断裂带。地震区内的解元集—小留集断裂与北面向的成武—定陶断裂构成共轭破裂导致菏泽５．９级地震发生，北东向断裂是其主要的发震构造。由菏泽５．９级地震前沿发震断层的ＭＬ≥３．０级地震震中迁移、震源深度的变化及跨断层形变测量资料表明，发震断层在区域构造应力场的作用下逐步克服障碍，使断层贯通，与此同时在发震构造断层面上，断层上盘向上逆冲，使应力最后集中在两条断层的交汇部位致５．９级地震发生。

It is concluded that there is a concealed large fault zone of N-E strike (shallow fault along south segment of Huanghe fault zone under the Heze seismic area) and the conjugate fracture of Jieyuanji-Xiaoliuji fault and Chengwu-Dingtao fault of N-E strike are the cause of ocurred Haze earthquake of Ms 5. 9, and the N-E strike fault of them is main seismogenetic structure, based on the data of recent seismogeology, geophysic exploration and satellite image. It is shown that the ocurrence of Ms 5. 9 earthquake is because of two cross faults concentrated stress caused by obduction of upper side along fault plan of seismogenetic structure, and gradually conquered asperity under the action of the regional structural stress field on the seismogenetic fault, exhibited by the data of epicentre immigration of ML≥3. 0 earthquakes along the seismogenetic fault, the change of focus depth and deformation measure across the fault.