The 22 January Zhenxiong Landslide: Slope stability analysis using Lutan-1 SAR Data

Abstract: A landslide occurred on January 22, 2024 in Zhenxiong county, China, resulting in 44 fatalities and the collapse of around 400 structures and buildings. Timely understanding of landslide formation mechanism is crucial for guiding emergency relief, disaster prevention and reduction, and post disaster reconstruction.This study evaluates the potential of China’s L-band SAR satellites (LuTan-1A/Lutan-1B) for slope stability analysis in Zhenxiong County based on R-index and sensitivity evaluation. Using stacking methodology and differential interferometry, the displacement velocity field is obtained. The results show that, by combination of LT-1 ascending and descending, the proportion of shaded areas in SAR imaging can be almost overcome, and the proportion of well imaged areas in SAR imaging for slope instability analysis is increased to 88.9%. The descending orbit data have poor visibility of Zhenxiong Landslide and weak sensitivity to the deformation measurement due to imaging distortions. The mean deformation obtained by stacking and cumulative displacement both indicate an instability zone at the top of the slope , where cumulative displacement reaches to around 200mm in 3 months before the failure. This  shift in trend of background deformation was larger than other parts of the slope, suggesting that the landslide was initiated by instability in the steep cliff area. The research findings are discussed which provide important insight for understanding the mechanisms of catastrophic failure in this part of ChinaKey words: InSAR, Lutan-1, landslide, SAR sensitivity