渤海及其邻区地震活动特征和构造涵义

本文利用新编 M_3>4(3/4)级历史地震目录及1970年以来 M_L>4.0级地震目录,对渤海及其邻区地震活动特征进行了分析。结果表明,地震图象及地震活动性参数的空间等值线显示该区地震主要受北西向天津—蓬莱断裂带和北北东向郯庐断裂带及其分支断裂的控制,而北西带的活动性更强烈;1970年以来4级以上地震在空间上沿活动构造带定向迁移与丛集,而以活动构造为基础划定的统计单元内4级以上地震随时间呈线性、指数或幂函数增长三种类型;海城和唐山大震发生于4级以上地震局部集中且呈指数增长过程中。结合地质构造及岩石破裂实验,讨论了上述地震现象的构造物理涵义及地震预报意义。

THE CHARACTERISTIC OF THE SEISMICITY IN THE BOHAI SEA AND THE ADJACENT REGION AND ITS TECTONIC IMPLICATION

By use of the newly-compiled historical earthquakes (M_S≥4(3/4)) catalogues and the cata-logues of earthquakes (M_L≥4.0) since 1970,the characteristics of the seismicity in the BohaiSea and the adjacent region are analysed.The earthquake pattern and the spatial contours ofseismicity parameters Show that the earthquakes in this area are dominated by the Tianjing-Penglai (NW) and the Tan-Lu fracture zone (NNE) as well as their branches,whereas the ac-tivity of the north-west belt is much stronger.The earthquakes with M_L≥4.0 since 1970 havemigrated and clustered along active tectonic belt.The earthquakes(M_L≥4.0) in statistic unit,which is delimited in the light of active tectonis,increase with time in the forms ofliners,exponential and power functions.The Haicheng earthquake and the Tangshanearthquake occur in the process of partial clustering and exponential increasing of earthquakeswith M≥4.0.The tectonic implication of the above seismic phenomena and its significance forearthquake prediction are discussed in combination with geological structure and rock fractureexperiment.