Review of Slope Monitoring Technology

This chapter summarizes the principles of early warning of landslides that are triggered slowly by gravity or rapidly by rainfall, whereas the details of warning technologies will be presented in later chapters. To begin with, the geometrical features of landslides are illustrated by using real events. Then, the importance of precursory displacement/deformation is stressed by presenting examples. Accordingly, it is stated that a forecast of slow gravity-induced landslides has been carried out by using a displacement criterion, which is exemplified by Saito’s creep model. This model has been developed to foresee the time of slope failure. In contrast, the rainfall-induced landslides occur rapidly, and the conventional approach for the gravity-induced landslide is not effective. To create novel technologies for rapid landslides, artificial rainfall tests have been conducted on slopes several times, and a new type of displacement criterion has been developed.