地震学报(英文版)
地震學報(英文版)
지진학보(영문판)
ACTA SEISMOLOGICA SINICA
2003年
4期
449-458
,共10页
郑金涵%宋胜合%刘克人%卢红艳%郭宗汾
鄭金涵%宋勝閤%劉剋人%盧紅豔%郭宗汾
정금함%송성합%류극인%로홍염%곽종분
gravity variation%dilatancy model%epicentroid%inversion
Gravity variation data observed in the process of seismogenesis and occurrences of earthquakes show that the location with the greatest gravity changes does not necessarily coincide with the epicenter. To explain this we defined the center of effective mass of stress volume as "hypocentroid", and the vertical projection of which on the earth's surface as "epicentroid".Here we adopt three rotating models, including spheroid, ellipsoid and cylinder, to represent the region of an impending earthquake. Based on the models of gravity variations induced by uniform dilatancy, epicentroids associated with sixteen earthquakes with M>4.0 occurred in 1981~2000 in the Beijing-Tianjin-Tangshan-Zhangjiakou region are determined by means of a proposed least squares iterative inversion method. The results indicate that cylinder model is preferable to the other two, and epicentroids obtained by the cylinder model separate from the epicenters by a range of 0~40 km. Epicentroids are inevitably located within intact tectonic blocks, and usually cluster in groups; while the epicenters are generally located at the terminations of faults or at the intersections of faults. It seems that there exist earthquake-hatching areas in the block among faults. Earthquakes hatch in these areas, but occur around these areas, meanwhile the existence of faults may play an important role in controlling the processes.