Precedent long-term gravitational deformation of large scale landslides in the Three Gorges reservoir area, China

Large scale landslides are common in the Three Gorges reservoir region due to steep slopes and complex geological conditions, fluctuations of reservoir level, etc. Many phenomena and formation mechanisms related to these landslides are not well understood and need more research. In this study, large scale landslide evolution and formation mechanisms are thoroughly investigated in terms of precedent long-term gravitational deformation (PLTGD). Three large scale landslides in the Three Gorges reservoir region, Huangtupo landslide (HTPL), Huanglashi landslide (HLSL), and Baotaping landslide (BTPL), are taken for example to discuss their phenomena and features of PLTGD, and to investigate the correlation between the PLTGDs and landslide. Many features associated with landslides are caused by slow, downslope gravitational processes before landslide failure, and three criteria for recognition of the PLTGD features are summarized. The investigation results reveal that the PLTGDs play an important role in landslide evolution and formation mechanism. Overall, this paper presents evidences for PLTGDs of large scale landslides and their correlation with landslide evolution, which is helpful to understand the formation mechanism of large scale landslides in the Three Gorges reservoir region.