关键词: 逆冲构造带, 纵向断裂, 横向断裂, 断裂分段, 阶地位相图

Abstract: Segmentation of thrust fault zone is a basic problem for earthquake hazard evaluation. The Yingjing-Mabian-Yanjin thrust fault zone is an important seismic belt trending northwest in the southeast of Tibetan plateau. The longitudinal faults in the thrust zone are mainly of thrust slipping. The late Quaternary motion modes and displacement rates are quite different from north to south. Investigation on valleys across fault shows that the transverse faults are mainly of dextral strike-slipping with a bit dip displacement. Based on their connections with longitudinal faults, three types of transverse faults are generalized, namely, the separate fault, the transform fault and the tear fault, and their functions in the segmentation of the thrust fault zone are compared. As the result, the Yingjing-Mabian-Yanjin thrust fault zone is divided into three segments, and earthquakes of the three segments are compared. The trisection of Yingjing-Mabian-Yanjin thrust fault zone identified by transverse faults reflects, on one hand, the differences in slip rate, earthquake intensity and pace from each segment, and the coherence of earthquake rupturing pace on the other hand. It demonstrates that the transverse faults control the segmentation of thrust fault zone to a certain degree, and each type of the transverse faults plays a different role.

Key words: thrust fault zone, transverse fault, longitudinal fault, fault segmentation, longitudinal profiles of river