Aerial photogrammetry is powerful technique to monitor landslide behavior effectively and safely. Using three dimensional displacement (3DD) vectors of ground points, which are detected by photographs taken at different time flights on a landsliding area, velocity and direction of ground movement can be visualized on a map or projection plane. Moreover, we can presume geometry of underground slide surface by analysis of the 3DD vectors. This paper treats a landslide that had abruptly occurred at Hirose in Nagano city. Its characteristic was small-area, rapid-growing, short-time movement. Survey-analytic system applied to this landslide demonstrates validity of the aerial photogrammtry.
