In this study, field geological surveys, high-resolution digital terrain investigations of microrelief variations,
and onsite monitoring were conducted from 2017 to 2020 to investigate the mechanics and mobility of a largescale
landslide located at Hong-Yeh Village in Taitung County. The results indicated that 91.9 million cubic meters of
unstable mass predominantly remained on the slope. Borehole inclination measurements conducted at the high-mobility
sliding block T001-C revealed two sliding planes located at 15-22 and 45-49 m, respectively, below the ground. A
conceptual model was therefore proposed on the basis of the landslide mechanics and detailed analyses of on-site
monitoring results, including rainfall, groundwater stage, borehole inclination, and surface displacement measurement.
The preliminary results indicated that amount of ground displacement was strongly correlated with accumulated rainfall.
Key Words: Hong-Yeh landslide, landslide characteristic analysis, large-scale landslide monitoring, landslide conceptual model.