渤海、黄海及沿岸强震聚类分析

CLUSTER ANALYSIS OF STRONG EARTHQUAKES OCCURRED IN BOHAI SEA,YELLOW SEA AND THE COASTAL AREAS

采用聚类分析方法，研究了渤海、黄海及沿岸强震（ Ｍ ≥６）的空间分布。研究结果划分出了强震活动区及一些离散发生的强震。渤海的强震往往参与河北、山东、辽宁沿岸的强震分期、分区活动，且以强度高为特征；南黄海强震区自成体系，存在多期活动，与沿岸强震关系不大，以频度高为特点；北黄海内呈弱活动区的状态；朝鲜半岛强震独立成区，未向黄海内部延伸。文中给出分区的构造解释，并提出海域强震存在时空差异。

The spatial distribution of strong earthquakes(M≥6)occurred in Bohai sea,Yellow sea and the coastal areas has been studied by the method of cluster analysis in the paper.Based on the results of study,the macroseismic active regions and some scattered strong earthquakes have been determined.The strong earthquakes occurred in Bohai sea are generally consistent with those occurred in the coastal areas of Hebei,Shandong or Liaoning provinces in period and region,and are characterized by high intensity;The south yellow sea macroseismic region has a style of its own with multiphase activities which is not related colsely to the coastal strong earthquakes and is characterized by high frequency;The North Yellow sea is a less active region;The Korean peninsula macroseismic region can be considered as an individual one which has not extended to the Yellow sea.Tectonic explanation for each region has been given in the paper and it has been proposed that space-time differences exist in strong earthquakes occurred in the sea area,so different countermeasures should be taken in earthquake prevention and disaster mitigation in the coastal areas and the sea areas.