临汾强震区地壳结构及发震背景研究

摘要

以诸城—宜川深地震测深速度剖面为约束，对沿该剖面得到的高精度重力数据进行拟合，并对临汾强震区平面布格重力异常进行处理，得到了该地区地壳密度结构及平面重力异常分布。利用上述结果分析了临汾强震区的地壳结构及构造环境，结合前人相关研究成果，认为临汾强震区地壳中存在塑性相对较强的介质，洪洞和临汾两次历史地震皆发生在其与周边弹性介质的转换边界上。另外，临汾凹陷南北两侧局部构造环境存在差异，在区域应力场作用下，导致了洪洞地震和临汾地震的发生。两次地震在发震时间、地点和震级等地震要素上有所不同。%Using the velocity profile of the Zhucheng--Yichuan deep seismic sounding (DSS)profile as a constraint to fitting the high precision gravity data along the profile,we processed the plane Bouguer gravity anomaly in Linfen meizoseismal area,and obtained the crustal density structure and distribution of the plane gravity anomaly in Linfen meizoseismal area.And then we analyzed the crustal structure and tectonic settings. In combination with previous research results,it is believed that there were more plastic crustal media in Lin-fen meizoseismal area,and the Hongtong and Linfen historical earthquakes all took place on the elastic-plastic transitional boundary.Moreover,there were differences between north and south sides of Linfen depression in local tectonic environment.Therefore,the Linfen and Hongtong earthquakes occurred under the regional stress field with different occurrence time,epicenter location and magnitude.