GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 The spatal distributon of seismicity is not uniform, but local clusters characterize it, as revealed by the fractal analysis and planes changing orientaton with tme, detected with the PCA method. The PCA solutons (Fig. 3) reveal mostly vertcal and sub-vertcal planes that ft the seismicity, changing orientaton from south to north. The fracture propagates within the fracturing plane in the southern part (zone 1), with the actvaton of parallel planes in the central part (zone 2) and along weakness lines in the northern part (zone 3). Therefore, the stress concentratons and the localizaton of seismicity appear to be controlled by the geometric interacton between faults and by sharp variatons of rock mechanical characters. Although performed in a narrow area and tme span, the adopted procedures and the resultng observatons can be applied to other areas of complex tectonics to investgate the tme evoluton of the seismicity and the damage. Acknowledgements The authors thank S. Urban and A. Magrin for help in graphics and critcal reading of the manuscript. The local seismic network is managed by the Seismological Research Centre of the Natonal Insttute of Oceanography and Applied Geophysics – OGS with the fnancial contributon of the Regione Friuli Venezia Giulia (Bragato et al., 2021). References Baiesi, M., Paczuski, M.;2004: Scale-free networks of earthquakes and afershocks , Phys. Rev. E., 69, 066106, doi:10.1103/PhysRevE.69.066106. Bragato, P.L., Comelli, P., Saraò, A., Zuliani, D., Morato, L., Poggi, V., Rossi, G., Scaini, C., Sugan, M., Barnaba, C., Bernardi, P., Bertoni, M., Bressan, G., Compagno, A., Del Negro, E., Di Bartolomeo, P., Fabris, P., Garbin, M., Grossi, M., Magrin, A., Magrin, E., Pesaresi, D., Petrovic, B., Plasencia Linares M.P., Romanelli, M., Snidarcig, A., Tunini, L., Urban, S., Venturini, E., Parolai, S.; 2021: The OGS–Northeastern Italy Seismic and Deformaton Network: Current Status and Outlook , Seismological Research Leters 92 (3), 1704–1716, doi:10.1785/0220200372 Bressan, G., Barnaba, C., Gentli, S., Rossi, G.;2017: Informaton entropy of earthquake populatons in northeastern Italy and western Slovenia , Physics of the Earth and Planetary Interiors, 271, 29–46, doi: 10.1016/j.pepi.2017.08.001 . Bressan G., Barnaba C., Peresan A., Rossi G.; 2021: Anatomy of seismicity clustering from parametric space-tme analysis . Physics of the Earth and Planetary Interiors 320, 106787, doi:10.1016/j.pepi.2021.106787. Bressan, G., Barnaba, C., Magrin, A., Rossi, G.; 2018a: A study on of-fault afershock patern at N- Adria microplate . J. Seismol., 22, 863-881, doi:10.1007/s10950-018-9737-x. Bressan, G., Barnaba, C., Bragato, P., Ponton, M., and Restvo, A.; 2018b: Revised seismotectonic model of NE Italy and W Slovenia based on focal mechanism inversion , J. Seismol., 22, 1563– 1578, doi:10.1007/s10950-018-9785-2 .