The landslides developed with the evolution of the river terraces in the loess plateau, China

摘要

Landslide investigation in the center part of loess plateau reflects that most of large-scale old and ancient landslides lie on river terraces at different heights, but the small ones usually occur along the sides of V-shaped loess valleys, which implies that there is an inherent connection between the landslides and the erosion action. Since river terraces were formed by intermittent uplift of the crust, which controls the features of river erosion and the thickness of loess on the terraces. The analysis of typical loess landslides in this region shows that during relative static period, lateral erosion was dominated, so river valley was widened, which induced some large-scale landslides because the toe of slope was strongly eroded. While during the uplift period, vertical erosion was dominated, and the loess began to deposit on the terraces above water level, with the downcutting of the river, a narrow V-shaped valley formed, and then small loess landsides occurred on both sides of the rivers. Therefore, intermittent crustal uplifts not only led to the formation of multi-degree of terraces, but also induce alternative occurrence of large-scale and small loess landslides.