Abstract: The Weihe Fault is an important blind fault in Weihe Basin and controls the formation,evolution and seismicity of Weihe Basin. The deep seismic reflection survey results show that the fault is not a deep crustal fault; it is located right below the C layer at about 15km depth and cuts through the crystalline basement and the C layer,causing a throw of about 4km between the two sides of crystalline basement. The dip angle at the shallow part of the fault(depth<5km)is big and flattens with depth,and the fault turns to be a listric fault.Shallow seismic survey results show that the dip angle of the Weihe Fault in the middle and deep parts is about 85°; the attitude is different on the two walls of the fault,the footwall is horizontal and the hanging wall is tilting to the south direction; and its dip angle increases quickly.Drilling survey results show that the fault at the shallow part is obviously manifested. The lithology,thickness and attitudes of strata are quite different between the two sides of fault. The attitude on the footwall is horizontal and that on the hanging wall tilts a bit to the fault side. The late Pleistocene displacement is about 4～6m.Trenching results show that the Weihe Fault near ground is still active. Since Holocene epoch it has undergone 3 paleoearthquakes and 1 history earthquake,so it is a Holocene active fault.

Key words: Weihe Fault, seismic prospecting, trench, tectonic manifestation

摘要： 渭河断裂是渭河盆地一条重要的隐伏断裂,对渭河盆地的形成和发展乃至盆地内的地震活动都具有一定的控制作用。文中基于横跨渭河断裂的深地震反射、浅层地震反射、钻孔勘探和槽探等勘探方法取得的探测结果,从深部、中部、浅部以及近地表4个深度,给出了渭河断裂的呈现特点,即最深切割层位、不同深度的产状变化、错距大小、断裂的最新活动时代和活动期次等。

关键词: 渭河断裂, 地震勘探, 探槽, 构造显示