GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 2.2 361 Fig. 2 – Plan view of the study area (Google Earth © vision) showing localisation of the geophysical measurements. Directional H/V analysis (the color scale is proportional to the amplitude of the H/V ratio), are reported. and the Lower Cretaceous units; a geological cross section shows the structural setting of the main units. Note the width (c. 50 m) and geometry of the studied fault zone. We reconstructed the architecture of the fault zone, by individuating different structural domains in the rock mass and then we evaluated the fracture intensity across the fault zone by correlating different structural-geometrical parameters (such as discontinuity spacing, discontinuity pervasivity, size of lithons, hardness index as provided by the Schmidt hammer). HVSR noise measurements. In Fig. 2 a plan view of the study area shows localisation of the geophysical measurements and in Tab.1 was reported a synthetic description of the results of noise measurements carried out in the study area. H/V measurements show a clear polarisation of ambient seismic noise. This polarization is centred mainly at about N120° (clockwise from North) and is nearly parallel to the strike of: i) the fault system; ii) the mapped fractures. Structural analysis. We selected eight exposures along the scanline corresponding to different geological-structural sectors within the fault zone. The most recurrent structural feature of the selected sectors is a set of NW–SE striking fault surfaces with dextral strike-slip kinematics Tab. 1 – Synthetic description of the results of noise measurements carried out in Guercino study area. # Amplitude Frequency Polarisation T11 <3 – – T10 <3 – – T4 4 6 Hz 130° T1 4-5 3 Hz 120° L5 4-5 2.5 Hz 40° T3 7-8 1.5 Hz 100° L8 <3 1.5 Hz 40° T2 3-4 1.3 Hz 90°