Additionally, besides the movement quantification and mass
balancing, important qualitative data can be obtained by digital
photogrammetry. It is clear from aerial photos captured before and
after reactivation (Fig. 6B and D), and even more apparent from
visualized 3D pictures (Fig. 6A and C), that the study site was affected
by several landslide events in the past and that 1977 reactivation
boundaries coincide with older ones. However, the area was probably
in the dormant stage for a century or more, and was therefore wrongly
judged as suitable for human activity (e.g. slope reclamation in the