Intermittent Stacking Method Improving Landslide Identification Capability in Low-coherence and Long-term Scenario

Landslides represent a significant natural and geological hazard, resulting in considerable economic losses and casualties on an annual basis. The frequency of landslide disasters has increased markedly in recent times due to intensified human activity. The China-Pakistan Karakoram Highway (KKH) is a vital component of the China-Pakistan Economic Corridor (CPEC), representing the sole land route connecting China and Pakistan. Due to the topography, destructive landslides occur on occasion along the KKH, and the identification of landslide hazards along the KKH has become a matter of urgency. InSAR technology is a highly effective method for landslide detection, offering excellent deformation detection capabilities. However, the coherence of the region is severely compromised by the complex terrain, geometric distortion, presence of snow and strong weathering transport, which presents a significant challenge for the application of traditional time-series InSAR techniques in this area. In this paper, the intermittent Stacking-InSAR (IStacking) method is proposed to obtain deformation data over the mountainous region of northern Pakistan, with a deformation data coverage of 97% in a time period of 6.5 years and an average coherence of 0.2. Utilizing the LOS deformation data and a landslide screening model, this paper identifies more than 150 suspected landslides in northern Pakistan, including over 10 landslides larger than 1 km² in area along the KKH. The subsequent validation of several large landslides was achieved through field visits and a comparison with Google images. Furthermore, the study identified that landslides along the KKH are characterized by high deformation velocity and large scale, which would cause significant damage to the highway and the residents living along it in the event of a collapse. In order to ensure the safety of these individuals and the continuity of the China-Pakistan Economic Corridor, it is necessary to assess the stability of the landslides.