GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 GNGTS 2023 In order to obtain the velocity structure from our revised dataset, we first determined the Vp/Vs ratio by using the arrival time pickings of selected P and S phases. The mean velocity ratio Vp/Vs was computed through the cumulative Wadati diagram. Then, by collecting all the a priori available information regarding the structure of Adriatic Sea (velocities, layer thicknesses and Moho depth), we applied the VELEST software (Kissling, 1995) to compute a new 1D velocity model for earthquake location. Conclusions In this work we present our first analyses of the sequence and the accurate study of the velocity models that we obtained from both a revision of available data and the inversion of arrival time pickings analyzed by the BSI analists. Moreover, we will discuss our preliminary earthquake locations with a particular attention to resolution analysis and hypocenter location assessment. References Christensen, N. I., and Mooney, W. D.; 1995: Seismic velocity structure and composition of the continental crust: A global view, J. Geophys. Res. 100, no. B6, 9761–9788. Coward, M.P., De Donatis, M., Mazzoli, S., Paltrinieri, W., & Wezel, F.C.; 1999: Frontal part of the northern Apennines fold and thrust belt in the Romagna-Marche area (Italy): shallow and deep structural styles. Tectonics, 18 (3), 559–574. De Nardis, R., Pandolfi, C., Cattaneo, M., Monachesi, G., Cirillo, D., Ferrarini, F., Bello, S., Brozzetti, F., & Lavecchia, G.; 2022: Lithospheric double shear zone unveiled by microseismicity in a region of slow deformation. Scientific Reports, (2022), 12:21066, https://doi.org/10.1038/s41598-022-24903-1. Di Stefano, R., E. Kissling, C. Chiarabba, A. Amato, and Giardini, D.; 2009: Shallow subduction beneath Italy: Three-dimensional images of the Adriatic-European-Tyrrhenian lithosphere system based on high-quality P wave arrival times, J. Geophys. Res., 114, B05305, doi:10.1029/2008JB005641. Di Stefano, R., Ciaccio M. G., Baccheschi P., Zhao D.; 2022: The Adriatic Thrust Fault of the 2021 Seismic Sequence Estimated from Accurate Earthquake Locations Using sP Depth Phases, Bull. Seismol. Soc. Am. XX, 1–14, DOI: 10.1785/0120220111 Kissling, E., 1995: Velest Users Guide, pp. 26, Internal report Institute of Geophysics, ETH Zurich. Lavecchia, G., Boncio, P., & Creati, N.; 2003: A lithospheric-scale seismogenic thrust in central Italy. J. Geodyn., 36, 79–94. https://doi.org/10.1016/s0264- 3707(03)00040-1. Mazzoli, S., Santini, S., Macchiavelli, C., and Ascione, A.; 2014: Active tectonics of the outer northern Apennines: Adriatic vs. Po Plain seismicity and stress fields, J. Geodyn. (2014), http://dx.doi.org/10.1016/j.jog.2014.10.002.