GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 GNGTS 2023 3D Scattering Attenuation Imaging of the Central Apennine 2016-2017 Seismic Sequence S. Gabrielli 1,2* , A. Akinci 1 , L. De Siena 2,3 , E. Del Pezzo 4,5 , M. Buttinelli 1 , Francesco Maesano 1 and R. Maffucci 1 1 Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy,  2 School of Geosciences, University of Aberdeen, Aberdeen, United Kingdom, 3 Institute of Geosciences, Johannes Gutenberg University, University of Mainz, Mainz, Germany 4 Osservatorio Vesuviano, Istituto Nazionale di Geofisica e Vulcanologia, Napoli, Italy,  5 Istituto Andaluz de Geofisica, Universidad de Granada, Granada, Spain,  Between August and October 2016, the Central Apennines (Italy) was struck by a cascading seismic sequence known as the Amatrice (Mw 6.0) - Visso (Mw 5.9) - Norcia (Mw 6.5) sequence (hereafter AVN). The sequence has been associated with fluid migration in the faults network (Miller et al., 2004; Di Luccio et al. 2010; Malagnini et al. 2012; Chiodini et al., 2020; Chiarabba et al., 2020). The analysis and the imaging of seismic attenuation parameters (e.g., scattering and absorption) are valuable tools for understanding the behavior of seismicity associated with fracturing and fluid migration. In this study, we investigate and present 3D images of the scattering contribution to the total attenuation of the seismic events of the Central Italy seismic sequence. The methodology is an extension of the 2D scattering imaging of Gabrielli et al. (2022), with the addition of the depth parameter, to obtain further information on the fracturing processes during the seismic sequence. Gabrielli et al. (2022) obtained a 2D mapping of peak-delay time and coda attenuation tomography in the same study area of the AVN, before and after the three major events to investigate the evolution of the sequence and which processes are controlling it. Peak delay, used as a scattering measurement, showed a substantial control on the scattering of seismic waves by main structural elements (e.g., Monti Sibillini thrust) and lithologies (e.g., Umbria- Marche and Lazio-Abruzzi geological domains). At the same time, the coda attenuation anomalies were associated with the deep migration of CO 2 -bearing fluids across the seismogenic zone during the seismic sequence in the fault network following the mainshock progression from south to north. As for the 2D, we used two datasets: the first one comprising ~4700 waveforms recorded before the sequence (March 2013-August 2016) and the second one comprising ~5370 waveforms (ML > 2.8) of the Amatrice-Visso-Norcia sequence (24 August 2016- 5 January 2017). This work aims to provide 3D scattering images in space and time for two datasets, one before the mainshock of Amatrice and a second during the sequence (August 2016-January 2017).