南华北地区地震活动特征分析

南华北盆地与秦岭大别造山带在构造上有耦合关系,地震活动水平相当。将南华北盆地和秦岭大别造山带组成的南华北地区作为研究对象,考察了其地震活动特征和青藏高原强震对其影响作用。发现南华北地区地震活动水平显著低于北华北地区,略低于下扬子地区。并且,通过对比分析青藏块体7.0级以上地震和南华北地区4.0级以上地震的对应关系,发现两个地区之间存在明显的成组对应现象,并表现2年左右的时间差,表明青藏块体的地震活动对南华北地区有明显的构造应力场传递作用。该结果为南华北地区中长期地震预测提供依据。2017年四川阿坝州九寨沟县发生7.0级地震,根据时间延迟的存在,对南华北地区未来中等地震的发生具有一定的指示意义。

Characteristic of Seismic Activities in the Southern North China

The Southern North China basin and Qinling-Dabie orogenic belt coupled structurally,and show the similar seismic activities level.In this paper,some effort was exerted to investigate the seismicity characteristic of the Southern North China,which comprises the Southern North China Basin and Qinling-Dabie Orogenic belt,and then some analogical analysis has been done to research the affinity between the large earthquakes with M≥7.0 in Tibet Plateau area and the middle earthquakes with M≥4.0 in Southern North China.The result shows that the seismicity level of Southern North China is markedly lower than the Northern North China,and slightly lower than that of the lower Yangtze block.And the earthquakes in Southern North China always correspond to the earthquakes in group in Tibet Plateau with a lag of approximate 2 years.The correspondence of the earthquakes of two areas indicates that the relationship of two areas exists through transmitting of tectonic stress field.In the other words,the large earthquakes in Tibet Plateau have significant indicative significance to following middle earthquakes in Southern North China.So much attention must be payed to possibility of middle earthquake in Southern North China because of the occurrence of Jiuzhaigou MS7.0 earthquake.