High resolution reflection seismics at the Patigno landslide, Northern Apennines, Italy

This work presents the results of a P-wave high-resolution reflection seismic survey at the Patigno landslide, a large landslide located in Northern Apennines, Italy. Due to previous geomechanical investigations, this area provides a suitable test site to verify the effectiveness of reflection seismic methods in characterizing a slope subsurface. Careful planning of data acquisition and a standard processing sequence allowed for a seismic section of the shallow subsurface to be built, which showed a reflection that was interpreted as the top of a highly deformed rocky layer. This rock layer favoured a deep-seated gravitational deformation, which affected a large sector of the slope. In addition to the available borehole data, this interpretation is also consistent with an electrical resistivity tomography profile that was acquired along the seismic line. Our results show that an ad hoc P-wave reflection survey can accurately delineate deep deformative surfaces, allowing for a more complete understanding of the mass movement phenomenon. This is particularly true for surfaces at depths sufficiently greater than the seismic wavelength, whereas for very shallow horizons, additional information (boreholes) or more impulsive sources (blasting caps) and more sophisticated techniques (S-waves reflections) are required for a reliable interpretation of the data.