渤海及邻区地震地质、地球物理场和地震活动特征

CHARACTERISTICS OF GEOLOGY,GEOPHYSICAL FIELD AND SEISMIC ACTIVITY OF BOHAI SEA AND ITS VICINITY

摘要:

对渤海及周围地区地质构造、地球物理场特征及地震活动特征进行了分析和研究.结果表明:该区域发育有NNE、NW和NWW向3组断裂.在渤海海域NNE向的郯庐断裂被NWW向断裂分割为3段,中段地震活动最强,发生过3次7级以上地震和3次6级以上地震.在空间上,地震活动可以划分为2个带,即郯庐地震带和燕山-渤海地震带.渤海中部地区热流值偏高,莫霍界面和康腊界面隆起,上地幔高导层埋深浅,为30~50 m.

Abstract:

Characteristics of geological structure,geophysical field and seismic activity of the Bohai Sea and its vicinity are analysed and studied.The results show three groups of fault of NNE,NW and NWW developed in the region.The Tan-Lu fault of NNE is divided into three section by faults of NWW.The seismicity is the strongest in the middle section among them.Three M≥7 earthquakes and three M≥6 earthquakes occurred in the section.The earthquakes are distributed along two belts,forming the Tan-Lu seismic belt and Yanshan-Bohai seismic belt.In the middle part of the Bohai Sea,the values of heat flow are the highest,the Moho discontinuity and the Conrad discontinuity have risen,depth of the low-resistivity layer of the upper mantle is 30~50 km,being mo re shallow.