晋冀蒙交界地区地震活动性特征分析

采用较为完整的地震资料,分析晋冀蒙交界地区地震活动性特征,结果表明,公元1929年以后,研究区的6.0级以上地震主要分布在河套地震带和张家口-渤海地震带上,在北纬40°线及附近区域形成优势分布区域,1970年以来的中等以上地震主要分布在内蒙古和林格尔-山西大同-河北张北形成的三角形区域内。研究区2005年9月以来中等地震持续1 304天的平静现象被2009年3月山西原平4.2级地震打破,岱海断陷1997年11月以来至今中等地震持续平静,统计结果显示,研究区和岱海断陷中等地震显著平静对研究区特别是河套地震带中强地震具有明显的指示意义,为显著的震兆标志,多种迹象表明,晋冀蒙交界三角形区域和呼和浩特-包头断陷为有利发震区域,发震强度或为6.0级左右。

Study on Seismic Activity Character and Trend in the Juncture Area of Shanxi,Hebei and Inner Mongolia

In this paper,characteristics of seismic activity in juncture area of Shanxi,Hebei and Inner Mongolia are analyzed,the results show that since1929,earthquakes with magnitude of MS≥6.0 in the area are mainly in the Hetao seismic belt and Zhangjiakou — Bohai seismic belt,at latitude 40 degrees and the surrounding area forms a dominant distribution area;Since 1970,the medium earthquakes are mainly distributed in a triangle region formed by Helinge＇er of Inner Mongolia,Datong of Shanxi and Zhangbei of Hebei.A seismic quiescence of moderate earthquake lasted 1304 days since September 2005 in the study area is broken by Shanxi Yuanping 4.2 earthquake;Daihai fault has sustained calm since November 1997.The moderate earthquake quiescence in study area and Daihai fault has obvious implications to medium earthquake of the research area and Hetao seismic belt,as a significant earthquake signs,a great deal evidences show that Shanxi,Hebei and Inner Mongolia triangle area as well as huhetaote—baotou fault are favourable zone of earthquake,the seismic intensity may be MS6.0.