抄録
Velocity, moving direction and spreading boundary of mass-movement are important factors for prevention and reduction planning of landslide disaster. Without surveying, there are no means to measure these factors. However, no field surveying is available when ground destruction by the landslide is violent and dangerous. To such a landslide suddenly occurred at Hirose district in the north-western part of Nagano city, photogrammetry was examined by flights on October 5-th and 10-th in 1989. Landslide behaviour was analyzed by finding three-dimensional displacements of tracing points on photographs taken by the two flights. Accuracy of the photogrammetry, error propagation to displacement vector of the tracing points, and landslide behaviour analysis by the vectors on projection planes were investigated. Applicability of the phtogrammetry to the analysis of sudden and violent landslide behaviour was demonstrated by these investigations.
