由多地震活动参数分析晋冀蒙交界地区长期地震危险性

Analysis onseismic risk of the border of Shanxi,Hebei and Inner Mongolia from multiple seismicity parameters

根据晋冀蒙交界近33年的区域台网地震资料,运用最大似然法,分别计算并绘制晋冀蒙交界1980年、1990年、2000年以来b值空间扫描图像,结果显示,低b值异常区主要分布在大同、张北、代县一带。依据区域地质构造条件、b值空间分布图像、历史强震和现代地震活动特征,将晋冀蒙交界分成张北段、延庆段、大同段和代县段4个段落,采用最佳效果拟合法+最大似然法,对各段落进行b值时间扫描,并且利用断裂带分段的多地震活动参数值组合分析方法,分析4个段落的现今活动习性,综合判定处于相对高应力和闭锁状态的断裂段。研究结果表明,张北段处于高应力背景下的相对闭锁状态,但会受到1998年、1999年张北M 6.2、M 5.6强余震影响。综合分析认为,需注意张北段和延庆段发生中强地震的长期地震危险。

Based onthe seismic catalog from regional seismic network in the last 33 years,we respectively calculated and drew b value spatial scanning image since 1980、1990 and 2000 using maximum likelihood method.The results show that low b value abnormal area is mainly distributed in Datong、Zhangbei and Daixian.Based on regional geological tectonic condition、b value spatial distribution image、historical earthquakes and Characteristics of modern seismic activity,we divided the border of Shanxi,Hebei and Inner Mongolia into Zhangbei、Yanqing、Datong and Daixian four sections,and calculated b value time scanning by using the best fitting method and the method of maximum likelihood,we analyzed the current seismicity characteristics of four sections by using the multiple seismicity parameter values of fault segmentation.Comprehensive judgement that the fault segment which relatively is in high stress and locking state.The results show that Zhangbei segment is in relative locking state under high stress background,but it is influenced by 1998、1999 Zhangbei M 6.2、M 5.6 strong aftershocks,we should pay attention to Zhangbei section.Comprehensive analysis that we should pay attention to the future occurrence risk of moderate-strong earthquake of Zhangbei section and Yanqing section.