Hr Reflection Surveys For Seismic Imaging Of Unstable Slopes

Abstract

Shallow seismic reflection survey is a powerful tool in revealing subsurface geometry of unstable slopes. A more or less accurate frame on discontinuities and a dynamic characterization of the investigated lithotypes is possible with this technique. This is of great importance for the reconstruction of the geological subsoil model, especially in cases of complex landslide stability analysis under seismic conditions. It proves it's overall value when compared to more classical geologic investigations (i.e. borehole drilling) which are not univocally interpretable in complex scenarios. Both P waves or SH waves can be exploited. P waves are normally applied in the presence of a strong difference in seismic impedance (lithoid materials). On the other hand, SH waves give better results where the seismic rigidity is not high (porous media). This note presents different applications of the technique in cases of modelling of unstable slopes throughout Italy. These can be considered representative of many landslide typologies. Illustration of adopted acquisition and processing parameters is given and data relevant to the geometry of seismic profiles is presented. Results are discussed and compared with geognostic borehole data and other common geotechnical methods, achieving a satisfactory reconstruction of the subsoil model.