GNGTS 2017 - 36° Convegno Nazionale

GNGTS 2017 S essione 1.1 89 propose that the different duration of seismic sequences is controlled by the type of energy released during the earthquakes, which is, in turn, related to the tectonic setting. Doglioni et al. (2015) proposed that extensional earthquakes are characterized by dissipation of gravitational energy, stored during the interseismic phase within a hangingwall volume confined by the main normal fault and an antithetic fractured dilated zone. When the stresses related to this gravitational energy exceed the strength of the dilated zone and of the main normal fault, the rock volume collapses slipping along the main fault, generating the earthquake. The downward hangingwall block movement happens in favour of gravity (e.g., Petricca et al. , 2015). The aftershock sequences can be interpreted as related to the rock wedge settlement due to the closure of fractures and to the complete dissipation of gravitational energy within the dilated antithetic zone. On the contrary, thrust-related earthquakes are characterized by dissipation of elastic energy, which is stored both within the rock volume above the thrust fault (i.e., the hangingwall block) and along the thrust fault itself during the pre-seismic period (e.g., Doglioni et al. , 2015). When the elastic energy exceeds the fault resistance, the hangingwall block moves upward along the fault against gravity, thus generating the earthquake; the elastic energy dissipation is buffered by the gravitational force. Finally, this comparative analysis of aftershock seismic sequences may be useful for seismic hazard assessment and, consequently, for the full understanding of long-term behaviour of an ongoing seismic sequence within different tectonic settings. References Doglioni, C., Carminati, E., Petricca, P. and Riguzzi, F.; 2015. Normal fault earthquakes or graviquakes. Sci. Rep., 5 . Kanamori, H. and Brodsky, E. E.; 2004. The physics of earthquakes. Reports on Progress in Physics 67, 1429. Mandelbrot, B. B.; 1989. Fractal geometry: what is it, and what does it do? In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 423, 3-16. Omori, F.; 1894. On the after-shocks of earthquakes (Vol. 7) . The University. Petricca, P., Barba, S., Carminati, E., Doglioni, C. and Riguzzi, F.; 2015. Graviquakes in Italy. Tectonophysics, 656 , 202-214. Turcotte, D. L.; 1986. Fractals and fragmentation. J. Geophys. Res., 91 , 1921-1926. Turcotte, D. L.; 1997. Fractals and chaos in geology and geophysics. Cambridge university press. Utsu, T.; 1961. A statistical study of the occurrence of aftershocks. Geophys. Magazine, 30 , 521–605. Utsu, T. and Ogata, Y.; 1995. The centenary of the Omori formula for a decay law of aftershock activity. J. Phys. Earth, 43 , 1-33. Computation of the rock volumes involved during the M w 6.5 Norcia earthquake E. Valerio 1 , E. Carminati 1 , R. Castaldo 2 , V. De Novellis 2 , C. Doglioni 1,3 , R. Lanari 2 , S. Pepe 2 , G. Solaro 2 , P. Tizzani 2 1 Department of Earth Sciences, Sapienza University of Rome, Italy 2 National Research Council (CNR), Istituto per il Rilevamento Elettromagnetico dell’Ambiente (IREA), Napoli, Italy 3 National Institute of Geophysics and Volcanology (INGV), Rome, Italy We analysed the seismic sequence that affects the Umbria-Marche Apennine (central Italy) since the August 2016, focusing on the M w 6.5 Norcia earthquake, nucleated along the Mt. Vettore extensional fault on October 30, 2017. We investigate the ground deformation pattern and the source geometry responsible of the 2016 central Italy seismic sequence by joint exploiting the multisensors and multiorbits satellite measurements (i.e. ALOS 2; e.g. Cheloni et al. , 2017) and their integration with the available geological/structural and seismological data. Starting from DInSAR (i.e. ALOS 2) and seismological data (i.e. hypocentral distribution and