Multivariate geophysical survey to detect a shallow fault zone in a landfill project area

Abstract

An integrated analysis of 2D high-resolution shallow seismic refraction tomographies (SRT) and electrical resistivity tomographies (ERT) has been carried out along a slope where the presence of a fault zone was assumed. It was also applied a post-inversion k-means cluster analysis of the P-wave velocity, the density of the seismic rays and the electrical resistivity of the interpretation models. Distribution maps of the cluster in multi-space were built, allowing to better definethe lateral geometry of a NE-SW directed band composed of intensely tectonized carbonate breccias. Finally, the fracturing and kinematic analysis on fault planes observed along the trenches, highlighted systems of left and right-lateral transtensional faults NW-SE, NNW-SSE and NE-SW trending, respectively, which antedate the extensional tectonic event. The reconstructed stress-field-orientation related to the latter tectonic system does not comply with the active stress field for this sector of the Sicilian chain. Moreover all the tectonic structures are sealed by Upper Pleistocene – Holocene continental deposits.