历史地震之余震参数的复核方法

基于主震和余震属于同一发震构造形成的震源区之原则,提出了历史地震余震参数的复核方法:首先在核实资料的基础上,判断是否属于余震;考虑主震震源区范围,综合确定余震震中位置,当资料不够充分时,也可直接以主震震中代替;按有感半径和区域烈度衰减关系来估算震级值.进而运用以上方法以1604年福建泉州海外7(1/2)级地震、1605年海南琼山7(1/2)级地震和1668年山东郯城-莒县8(1/2)级地震的13次余震为例,探讨了此方法的普适性.结果表明13次余震中有12次地震震中位置和6次地震的震级值发生了变化,使得原有余震参数的不确定性得到了明显改变,判定了主震和余震是属于同一发震构造.这些结果为在相关地区合理识别发震构造创造了条件,也可为今后修编历史地震目录提供参考.

Review Methods for Aftershocks Parameters of Historical Earthquakes

Based on the principle that the formation of the source area of the main shock and aftershocks are of the same seismogenic structure, this paper proposes some review methods about aftershocks parameters of historical earthquake. First is the verification of the information the aftershocks: the scope of the source region of the main shock is taken into account before the integrative determination of the location of the aftershocks. When information is insufficient, it can be directly used in epicenter of the main shock; and felt radius and regional intensity attenuation relations are used to estimate the magnitude. By using the above approach to more than 13 aftershocks in 1604 M11A offshore Quanzhou earthquake, 1605 M11A Qiongshan earthquake in Hainan and 1668 M81/2 Tancheng-Juxian earthquake in Shandong, this paper discusses the generality of the methods. The results show that out of these 13 aftershocks, epicenter locations of 12 earthquakes and magnitudes of 6 earthquakes have changed. As a result, the uncertainty of the original parameters of aftershocks have undergone a significant change, pointing to the fact that the main shock and aftershocks are of the same seismogenic structure. These results created conditions for reasonably identifying seismogenic structure in the relevant areas, and in preparation for revising the earthquake directory in the future.