An alternative approach to the study of deep mechanism of large-scale mass movements

Abstract

In complex large scale mass movements the presence of surficial deformations and/or displacements have never been used for the definition of deep mechanisms and their kinematics. The aim of the research in progress is to try to define a reproducible system, of study and analysis, of such phenomena, which can be applied to in complex geological-geo-morphological situations. The proposed methodology is based on aerophotogrammetry survey data; in particular from data obtained by pre- and post-event flights. The topographical variations of the subject area of a landslide can be modelled in a digital form. Starting from simple models of different landslide typologies (rotational, roto-translational, etc.) and analysing the plano-altimetric variations, before and after the movements and the consequential distribution of displacement vectors, it was possible to create a preliminary classification of the type of slope movements, and to give some indications as to the probable depth of rupture surfaces. The possibility of processing a complex landslide, by breaking it down into simplified kinematic models using polynomial fitting techniques or Fast Fourier Transform analysis and successive filtering steps, gives results of relevance for future research aims. As real application of such a method we propose the example of the 1982 Ancona (Central Italy) landslide. A great deal of topographic data already existed regarding this large mass movement.