Hysteresis effect and seasonal step-like creep deformation of the Jiuxianping landslide in the Three Gorges Reservoir region

Slow-moving landslides are common in the Three Gorges reservoir (TGR) region. It may evolve into massive landslide hazards due to reservoir level fluctuation and rainfall. The assessment of slow-moving reservoir landslides is critical for the prevention and control of geological hazards. A step-like deformation mechanism for slow-moving landslides is proposed. Here, we use various wavelet tools to process the time series of 16 years continuous monitoring surface displacement of the Jiuxianping landslide at TGR. Then, the methods are used to investigate the correlation and hysteresis between the trigger factors (rainfall and reservoir level fluctuation) and reservoir landslide creep displacement. Owing to the influence of reservoir level fluctuation and rainfall, the triggering factors of displacement in different regions differ and show prominent hysteresis characteristics. Furthermore, the contribution of GPS monitoring points and InSAR fusion technology to creep landslide assessment is discussed, which can effectively reduce the possibility false alarms in landslide prediction. These mechanisms can be used to explain why some sliding bodies can keep stable after very large and long-time deformation. Therefore, these results are crucial for effective and reasonable geological hazard prevention and control in the TGR region.