利用天然地震震源点确定活动断裂深部延伸性状的尝试

本文首先运用卫星影像,对临汾—运城盆地中主要活动断层的平面展布状况进行了解译。在此基础上,利用天然地震震源点的三维生标,探索性地研究与确定了各条断层的深部延伸性状,建立起了盆地内断裂构造的三维格架。主要结论有:(1)边缘断裂多数是深达莫霍面的(38km)伸展性铲形断裂;(2)霍山西麓山前大断裂的深部延伸为直立状,深度达莫霍面(38km)。(3)盆地内的其它断层多数是铲形断层的对偶断层,产状为倾斜状,与铲形断层相遇后而终止,延伸深度一般不超过30km;(4)区内存在4个水平滑脱面(或层),其深度分别为4.5～5.5km,9.5～10.5km,18.5～20.5km,35.5～37.5km,这些面(或层上)震源点分布较密集;(5)区内北部、中部、南部,断层组合形式稍有差别,并控制、形成了不同的地貌形态。

A try of determining active faults extensions in depth by earthquake focuses

In this paper, at first, the plane distribution of main active faults in the Basin of Linfen-Yuncheng are interpreted by satellite imagery. Then, their extensions in depth are tentatively studied, and determined by using the three-dimension coordinates of focuses. Finally, the three-dimension frame of fault structures in this basin is built.The main research results show that: (1) most basin-margin faults are listric faults, deep down to the Moho discontinuity surface (38km).(2) Huoshan west-margin fault is perpendicular fault, and deeps down to the Moho discontinuity surface (38km). (3) The other faults in the inner parts are mainly antithetic faults of the listric fanlts. They are dip normal faults, deep down to the surfaces of the listric faults. Their exiension depths are usually lower than 38 km. (4) There are four horizontal slipping surfaces (or layers), namely, 4. 5-5. 5 km, 9. 5-10. 5 km, 18. 5 - 20. 5 km, 35.5 - 37.5 km. Focuses distribute densely on the surfaces (or layers) (5) The composite pattern of faults in the north, centre and south of the district are little different. They control and form different landforms.