Evolution of deep-seated landslide at Putanpunas stream, Taiwan

This study used multi-stage remote sensing data in the analysis of the evolution of deep-seated landslides at Putanpunas stream, Taiwan. Terrain analysis, landslide interpretation, and the assessment of underlying mechanisms were included. Our results show that the evolution of deep-seated landslides can be divided into four stages: (1) erosion and decompression of the gully, (2) deformation of the rock slope, (3) the development of sliding surfaces, and (4) movement of the sliding mass. A large quantity of colluvium has accumulated on the slopes and in upstream and midstream gullies. In the future, we predict that the erosion of this colluvium will greatly influence the direction of flow and terrain in the alluvial fan. This activity is also expected to threaten the safety of inhabitants and property in the area intersecting Laonong stream.