GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 1.2 171 to estimate the locking depth (LD) and dip-slip rate of the fault model. We test two scenarios: a first model with only the Bassano-Valdobbiadene thrust fault accumulating elastic strain (Model 1) and a second model with a 3-fault system, adding to the BT the ramp-décollement system pertaining to the Montello thrust (Model 2). Fig. 3 displays the inversion results with the Model 1, showing that the horizontal and vertical velocity gradients are decently reproduced with the simplest dislocation model. This result suggests that the BT may accommodate elastic seismic deformation with an estimated slip rate of ~2 mm/yr. The data inversion with Model 2 provide similar results to Model 1, except for a slight better fit of data located above the Montello hill. In the second model the LD of BT is ~8 km with same slip rate and the Montello thrust has a very shallow LD (~3 km) with a sub-mm slip rate (~0.5 mm/yr), in agreement with previous results showing a limited locking for the Montello thrust ramp (Serpelloni et al. , 2016) All the results will be discussed in terms of seismic potential of the considered fault systems in comparison of the available geological and geomorphological information, and providing some explanations on systematic residuals we obtain in the datasets modeling. References Berardino P., Fornaro G., Lanari R. and Sansosti E.; 2002: A new algorithm for surface deformation monitoring based on small baseline differential SAR interferograms. IEEE Trans. Geosci. Remote Sens., 40, 2375-2383 Castellarin A., Nicolich R., Fantoni R., Cantelli L., Sella M. and Selli L.; 2006: Structure of the lithosphere beneath the Eastern Alps (southern sector of the TRANSALP transect). Tectonophysics 414, 259–282 Danesi S., Pondrelli S., Salimbeni S., Cavaliere A., Serpelloni E., Danecek P., Lovati S. and Massa M.; 2015: Active deformation and seismicity in the Southern Alps (Italy): The Montello hill as a case study. Tectonophysics 653, 95–108. doi:10.1016/j.tecto.2015.03.028. DISS Working Group (2018). Database of Individual Seismogenic Sources (DISS), Version 3.2.1: A compilation of potential sources for earthquakes larger than M 5.5 in Italy and surrounding areas. http://diss.rm.ingv.it/diss/ , INGV, doi:10.6092 /INGV.IT -DISS3.2.1 Galadini F., Poli M.E. and Zanferrari A.; 2005: Seismogenic sources potentially responsible for earthquakes with M≥ 6 in the eastern Southern Alps (Thiene-Udine sector, NE Italy). Geophysical Journal International 161, 739–762. doi:10.1111/j.1365-246X.2005.02571.x. Fig. 3 - Cross sections across the Montello and Bassano- Valdobbiadene thrust faults showing the results obtained using a 2D dislocation model for the Bassano thrust (Model 1)