A Novel Approach to Determining Annual Failure Probability of Landslide Based on Time-Series InSAR and Its Application in Landslide Risk Assessment

Quantitative landslide risk assessment is a critical step in hazard prevention and mitigation, as well as in informing government decision-making. However, the complexity involved in determining the annual failure probability poses substantial challenges in assessing both individual and societal risks in landslide areas. This study proposes a new method for estimating the annual failure probability based on time-series InSAR deformation data and modified inverse velocity analysis. The ground deformations and deformation velocity time series are first studied with Interferometric Synthetic Aperture Radar (InSAR); then, the onset of acceleration creep and the time of failure are determined through the time series deformation curve and the modified inverse velocity analysis; as such, the annual failure probability can be estimated based on the time of failure; finally, the individual and societal landslide risks are quantified through analyses of the elements at risk and the F-N curve. To illustrate the effectiveness of the proposed method, the risk assessment of the Bailing landslide in Xiangning County, China, is conducted. It was observed that the Bailing landslide has exhibited a general deformation trend since early 2020, primarily due to the influence of surrounding coal mining activities. The estimated annual failure probability of the Bailing landslide is 0.1, with an individual risk of 4×10⁻⁴ per year. The societal risk associated with landslide failure falls within an unacceptable range according to the F-N standard established by Hong Kong. Considering the impact of coal mining activities on the stability of the Bailing landslide, it is essential to implement more comprehensive and frequent deformation monitoring in the future.

Keywords: InSAR, Slope annual failure probability, Landslide risk quantitative assessment.