Seismic investigation on landslide is hampered by several factors that could
prevent the use of the reflection seismic method to characterize the subsurface architecture
(Jongmans and Garambois, 2007). Moreover, acquisition and processing of reflection seismic data
are more time consuming compared with other geophysical techniques such as refraction seismic
and electrical resistivity tomography (ERT), leading inevitably to higher costs. Notwithstanding
these difficulties, recently some attempts to delineate the deep slip surface of large landslides have
been carried out using P-wave reflection seismic surveys (Apuani et al., 2012; Stucchi and
Mazzotti, 2009; Stucchi et al., 2014;). P-wave reflection seismic method is effective in imaging the
slip surface at a depth sufficiently greater than the seismic wavelength, whereas, for very shallow
horizons, it suffers from the limited resolution that can be obtained by the use of compressional
waves. In this regards, SH-waves can be used to overcome this limitation (Deidda and Balia, 2001;
Guy, 2006; Pugin et al., 2006,), but they require a specifically-designed energy source for waves
generation, geophones measuring horizontal components of particles motion and an accurate choice
of acquisition parameters. On the contrary, due to attenuation, the depth of investigation for SHwaves
can be lower than for P-waves (Pugin et al., 2006). Therefore the geological understanding of
a mass movement can take advantage of a combined use of both these geophysical methodologies.
This is the case of the Patigno landslide, a great landslide located in the upper basin of Magra River,
in the Northern Appennines, Italy (Fig.1), where a P-wave study carried out in the last years
(Stucchi et al., 2014) was able to image the deepest discontinuity of the landslide body at around
40-50 m depth, but no description of the shallower layers can be inferred. Because these surface
layers are the slip surfaces of quick reactivation movements of the landslide, an SH high-resolution
reflection seismic survey was planned along the previous P-wave profile (Fig.1). This new survey
associated to the P-wave investigation allows a more robust description of the landslide body, from
the deepest discontinuity up to the very shallow portions of the landslide.
This work describes the planning, acquisition and processing of the SH reflection seismic survey,
and also gives a possible combined interpretation of both P and SH seismic images