GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 1.3 211 This is the case of East Tyrrhenian margin and especially for Neapolitan volcanic area, where the Mohorovičić discontinuity is very shallow (Solaro et al ., 2007). In this context, the aseismic zone could be explained in terms of the rheological continuum of the ductile region from the mantle depth to the very shallow magma intrusion. In the last section of present study, we investigated if the rheological properties of the rock succession could play a role in the deformation style of the volcano and in the modulation of the long-term ground deformation pattern that affects Ischia Island. To this purpose, starting from the computed the B/D transition, we performed a FE fluid dynamic model under viscous flow approximation. The proposed model assumes that the spatial and temporal evolution of the long-term subsidence phenomenon is modulated from a coupling action due to the volcano loading and the crust rheology In this scenario, the model indicates a lateral mass migration induced by the presence of the shallower ductile region; in addition, a decrement of the subsidence rate at this depth is highlighted. We interpret this tendency as the joint effect of the viscosity heterogeneities of the crust beneath the Island and the asymmetric morphology of the volcano edifice (Castaldo et al ., 2017). This scenario is also in a good agreement with the onset of normal fault systems around the resurgent block and the general extensive trend that affects the volcanic Island. References Carlino, S., Somma, R., Troiano, A., Di Giuseppe, M.G., Troise, C., De Natale, G., 2014. The geothermal system of Ischia Island (southern Italy): critical review and sustainability analysis of geothermal resource for electricity generation. Renew. Energy 62, 177–196 R. Castaldo, G. Gola, A. Santilano, V. De Novellis, S. Pepe, M. Manzo, A. Manzella, P. Tizzani (2017). The role of thermo-rheological properties of the crust beneath Ischia island (Southern Italy) in the modulation of the ground deformation pattern. Journal of Volcanology and Geothermal Research. DOI 10.1016/j.jvolgeores.2017.03.003. Ranalli, G., 2001. Rheology of the Earth. second ed. Chapman & Hall, London. Solaro, G., Tizzani, P., Milano, G., Pauselli, C., 2007. Rheological behaviour of the crust in SouthernApennine (Italy): results from a thermal and seismological study. Terra Nova 19, 353–359.