In the slate belt of Taiwan, there have been numerous studies exploring landslide activity or gravitational slope deformation (GSD) since the 2009 Typhoon Morakot. However, studies evaluating the relationship between present-day activity and long-term deformation have been infrequent due to a lack of multi-temporal monitoring data and analysis tools. The Chingjing region, which contains many GSDs and famous rockslides, is one such region that requires further investigation in this context. This study aims to interpret the evolution of slate slope deformation from long-term kinematics to short-term activity. We first observe the surficial displacement rate during the period of 2018-2020 using multi-temporal InSAR analysis. The radar satellite-based surface observation was then supplemented with numerical analysis based on the distinct element method to characterize the sub-surface gravity-driven slope movement. Our results help explain the evolution of gravitational slope deformation in slate slopes and better assess rockslide hazards transferred from GSD.
Central Range slate belt is the most dynamic and has diverse topographic among the geological environments in Taiwan. The response of landforms throughout the slate belt of Taiwan to ongoing GSD is regulated by mechanical and geometric properties of the tectonic foliations. This endogenic process within the slate slopes not only dominates landscape evolution but also plays a critical role in associated large or secondary landslides. The Central Geological Survey of Taiwan has recognized over 35,000 landslides occurring in this area during 2009 Typhoon Morakot (Huang et al., 2016). The Lushan North Slope, which is located in the Chingjing region (Fig. 1), is identified as the key large landslide by the Soil and Water Conservation Bureau and often activated by torrential rainfall events. Although numerous studies contributed to the hazard mitigation in the Lushan North Slope (Chang et al., 2015; Lin et al., 2020; Lu et al., 2014), other slate slopes in the Chingjing region such as Dingyuan and Shouting domains are less discussed because lack of multi-temporal monitoring data and analysis tools (Fig. 1b). This study integrated radar satellite-based surface observation and mechanical modeling to interpret the evolution of slate slope deformation from long-term kinematics to short-term activity in these domains. The results are expected to facilitate the assessment of rockslide activity associated with the GSD in the slate slopes.
