濮阳小震集中区地震丛集特征分析

Study on the characteristics of earthquake clustering in small earthquake concentrated area of Puyang

利用濮阳小震集中区1970年1月-2019年12月地震目录,基于最邻近事件距离算法计算地震丛集率,分析该区地震丛集特征。结果发现:(1)在中强地震前,濮阳小震集中区地震丛集率存在高值现象,而后出现不同程度的低值,与强震前地震活动从增强到平静的过程相吻合,对地震危险区判定有一定指示意义;(2) 1997年以来,4级以上地震主要分布在聊城-兰考断裂西侧,且小震出现相对"稀疏"异常,应给予关注。

Based on the earthquake catalogue from January 1970 to December 2019 in the small earthquake concentrated area of Puyang, the clustering rate of earthquakes is calculated based on the nearest event distance algorithm, and the clustering characteristics of earthquakes in the small earthquake concentrated area of Puyang are studied and analyzed. The results show that:(1) the clustering rate of small earthquakes in Puyang area is high before moderate earthquakes, which is often regarded as a signal of strong earthquakes or tectonic activities;and then there are low values in different degrees, which is consistent with the process of seismicity from enhancement to calm before strong earthquakes, and this feature has a certain indication significance for determining the seismic hazard area;(2) Since 1997, earthquakes with M ≥ 4 are mainly distributed on the west side of Liaocheng-Lankao fault, and small earthquakes appear relatively "sparse" anomalies, which should be paid attention to.