GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 3.1 577 fault characterization, the adopted multi-scale approach enables us to evaluate the consistency and robustness at depth of the ERT inversion results. The advantage of this approach is that different spatial resolution and investigation depths provide useful information at different structural levels, and therefore they can be used to characterize the fault behaviour at different time-scales. Notwithstanding the novelty and the effectiveness of the presented multi-scale electrical approach, the ERT methods are routinely adopted for active tectonic studies. Using probes hammered into the ground, ERT survey operations can be laborious and time-consuming, especially if the goal of the geophysical survey would be the imaging of the very near surface resistivity picture of the fault across its entire areal extent. As matter of the fact, we tested the capacitive-coupled resistivity methods (CCR) over the Piano Grande Castelluccio fault splay activated after the 30 October Mw 6.5 earthquake. Resistivity measurements were made along parallel profiles by towing a dipole array with constant transmitter-receiver separations. Recovered CCR resistivity model are in accordance with 2-D resistivity picture of the fault splay as obtained from ERT data (not shown here). We are confident it can be successfully applied for a fast and high-resolution resistivity imaging of a fault splay over a large area, which could be useful also for siting new paleoseismological trenches. References Biella G., Lavecchia G., Lozey A., Pialli G., Scarascia G.; 1981: Primi risultati di un’indagine geofisica e interpretazione geologica del Piano di S. Scolastica e del Pian Grande (Norcia, PG). In: Atti I ConvegnoAnnuale GNGTS, 293-308. Cesi C., Di Filippo M., Di Nezza M. and Ferri M.; 2010: Caratteri gravimetrici della media Valle del Fiume Aterno, in icrozonazione sismica per la ricostruzione dell’area aquilana . Gruppo di Lavoro MS–AQ Ed., Regione Abruzzo –Dipartimento della Protezione Civile, L’Aquila, vol. 3. Christiansen A.V., Auken E.; 2012: A global measure for depth of investigation . Geophys., 77 , 171–177. Civico R., et al. ; 2017: Geometry and evolution of a fault-controlled Quaternary basin by means of TDEM and single- station ambient vibration surveys: The example of the 2009 L’Aquila earthquake area, central Italy . J. Geophys. Res.,  122 , 2236-2259. Di Giulio G., Gaudiosi I., Cara F., Milana G. and Tallini M.; 2014: Shear-wave velocity profile and seismic input derived from ambient vibration array measurements: The case study of downtown L’Aquila. Geophys. J. Int., 198 , 848–866. Improta L., et al. ; 2012: High-resolution controlled-source seismic tomography across the Middle Aterno basin in the epicentral area of the 2009, Mw 6.3, L’Aquila earthquake (central Apennines, Italy). Ital. J. Geosci., 131 , 373–388. Nakamura Y.; 1989: A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface. Railway Tech. Res. Inst. Quart. Rep., 30 , 25–33. Pucci S., et al. ; 2016: Deep electrical resistivity tomography along the tectonically active Middle Aterno Valley (2009 L’Aquila earthquake area, central Italy). Geophys. J. Int., 207 , 967–982. Sapia, V., Viezzoli A., Menghini A., Marchetti M., and Chiappini M.; 2015: The Italian reference site for TEM methods. Ann. Geophys., 58 , G0548). Villani F., and Sapia V.; 2017: The shallow structure of a surface-rupturing fault in unconsolidated deposits from multi- scale electrical resistivity data: The 30 October 2016 Mw 6.5 central Italy earthquake case study. Tectonophys., https://doi.org/10.1016/j.tecto.2017.08.001