【摘要】 地震破裂后,破裂区应变能是否已经充分释放,能否在破裂面内再次发生震级接近的地震,是双主震研究的重要问题.通过对2003年云南大姚两个地震序列的双差定位,发现余震区扩展,但两余震区无论在深度上还是在水平位置上基本不重叠.又通过相对定位的方法,发现7月21日主震位于10月16日主震的北西西方向.此外,还通过P波初动极性分析的方法,发现两次主震破裂面的走向略有差别,这与余震区重定位后的分布一致.这些结果表明,大姚两次地震有可能发生在断层系统的不同段落上,虽然距离很近,但是两破裂区基本没有重叠.更多还原

【Abstract】 After an earthquake,has the strain energy in the rupture zone been fully released? Will there be another earthquake with similar magnitude occurring on the same fracture surface? These questions are important issues concerning earthquake doublets.In this paper we relocated the 2003 Dayao two earthquake sequences with double-difference location algorithm(HypoDD),and found that the aftershock zones have expanded,but the two aftershock zones hardly overlap in both depth direction and horizontal direction.The DD relocation result also shows that the July 21 mainshock is to the northwest of the October 16 mainshock.In addition,P-wave polarization analysis result indicates that the fault plane strikes of the two mainshocks deviate slightly from each other.This is consistent with the situation of aftershock zone stretching.These results imply that the two Dayao earthquakes,which are near enough,may have occurred in different segments of a fault system.It can be assumed that these two rupture zones are not overlapped.更多还原