Conclusions
A quadrangular seismic array allows exploring the subsoil structure using seismic refraction and seismic interferometry methods. We apply these methods to obtain velocity distribution images (Vp and Vs) of materials prone to landslides. The refraction method helps determine the bedrock depth, which can also be inferred into the array by taking advantage of surface sources and receiver geometry. At the study site, the surface waves generated from an active source and extracted from the ambient noise allowed to delineate the extent of materials close to sliding, whose Vs values are less than 200 m/s and notably contrast with the area of more compact materials.
We find the best Vs velocities correlation obtained from both methods is observed on an average frequency of 24 Hz. Future research will analyze the differences due to the surface waves character and produce a 3D-Vs model. We can point out that in the case of a high risk of landslide, when it is not advisable to induce stress into the subsoil, ambient seismic noise can provide practical results to determine the extension of the sliding materials.