# Study on Temporal and Spatial Distribution of Landslides in the Upper Reaches of the Yellow River
## 5 Discussion  
From the above 4 sections, it can be seen that the cluster of giant landslides in the study area is widely distributed, and analyzing the inducing factors of giant landslides will help guide the prevention and control of giant landslides. This paper discusses the induced factors of giant landslides from the Yellow River erosion effect, historical earthquakes, and modern human engineering activities, taking the Xichengt giant landslide as an example. The Xichengtan giant landslide is located in the transitional zone between the mountainous area and the river valley on the north coast of the Yellow River in the central part of the Guide Basin and east of the Nongchun River, a first-class tributary of the Yellow River. The terrain at the back edge is high and steep, with a maximum elevation of 3150 m, while the front edge extends to the bank of the Yellow River, with an elevation of about 2220 m and a relative difference in elevation of more than 900 m. The lithology of the basement strata in the landslide area is mainly Proterozoic and Triassic strata, overlying the Xining Group of Paleogene purple sandy conglomerate, sandstone, and silty mudstone. Above the Xining Group, a set of Guide Formation, Quaternary Republican Formation, and Residual Slope Formation with a total thickness of more than 1000 m, dominated by sandstones, conglomerates, and mudstones is unconformably overlain [29; 30; 31]. The strata exposed in the landslide area are the Pliocene Guide Formation and the Holocene Floodplain (Figure 10). The slide bed is mudstone, sandstone, and marl of the Pliocene Guide Formation, which is in the form of a layer structure, with a thickness of 0.3-0.5 m in a single layer, weathering is serious, and the yield is 358\({}^{\circ}\angleangle 3^{\circ}\). During the uplift of the Tibetan Plateau, the northern side of the Yellow River in the Guide Basin has a steeper slope than the southern side due to the differential up-lift of the northern and southern sides of the basin [32]. The Yellow River channel is close to the north side of the mountain in the basin (Figure 11). The Yellow River has a strong lateral erosion effect on the north side of the mountain, so it is easy to form a high and steep slope on the left bank, which has the free-face condition for landslide development. The stratigraphy of the Neoproterozoic Guide Formation on the north bank consists of sandstones, mudstones, and marl, which are prone to destabilizing the strata under the stripping effect of the Yellow River, resulting in a sit-down slide. The study shows that in the early Holocene, the rapid warming of the Tibetan Plateau and ice and snow meltwater led to an increase in the amount of water coming from the upper reaches of the Yellow River, the hydrodynamic energy increased significantly, and the erosion effect on the north bank was enhanced. The early Holocene was also a period of concentrated development of landslides in the upper reaches of the Yellow River in the Lagan Gorge-Shi Gou section [33]. Since 1709 A.D., the study area has entered a period of frequent earthquakes and other natural hazards, and earthquakes have been occurring continuously within the Guide earthquake under the influence of the Ashigang-Dechenji active rupture, which has been strongly active since the Holocene [34]. In particular, the 1872 A.D. Guide earthquake caused the dust raised by landslides in the Beishan area of Guide to cover the sky. Therefore, earthquakes are often capable of triggering mega-giant landslides, such as the Daguangbao giant landslide triggered by the Wenchuan earthquake of 12 May 2008 [35] and the Baozi village landslide triggered by the Minxian earthquake of 2013 [36].