临汾地区现代地震活动与构造的关系

Relationship Between the Moderate Earthquakes and Deep-Seated Structures in Linfen Area

一、地质背景临汾盆地及其周邻地区(北纬35°40'—36°30',东经111°00'—112°00')挽近构造活动十分强烈,是汾渭地震带中历史中强地震的主要活动区域之一。研究区北部为临汾凹陷、南部是襄汾隆起和河津凹陷的北部,东西分别以大断裂与霍山、罗云山相连接(图1)。其中,临汾凹陷是临汾盆地中的主体构造单元。中新世沉积物厚度和早更新世湖泊顶面高程计算以及黄土冲沟分形几何学分析分维值表明,它的下降幅度和速度都在整个盆地中居首位,并在广胜寺—洪洞附近和龙祠—临汾—带。

In this paper, the basic structure characters of deep-seated structure in Linfen area are analyzed based on surface geological and deep-seated geophysical data. On the base of three dimensional distribution character of moderism earthquakes since 1970 in the area, We considered that the surface distributions of hypocenter and depth of focus have close relationship with step structure of the basin, and proposed that there are eight layers possible which are known as "multiseismical layers" , among others, the L_4, L_5, and L_6 layers (depth: 18—28km) are main seismically active positions in the crust of this area. Finally, we suggested that there exists some difference between focus structure of multiseismical layers and surface structure form.