EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

The impact of tectonic structures on the 3D scattering imaging of the Central Italy Seismic Sequence

Simona Gabrielli1,2, Aybige Akinci1, Luca De Siena2,3, Edoardo Del Pezzo4,5, Mauro Buttinelli1, Francesco Maesano1, and Roberta Maffucci1
Simona Gabrielli et al.
  • 1Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
  • 2School of Geosciences, University of Aberdeen, Aberdeen, United Kingdom
  • 3Institute of Geosciences, University of Mainz, Mainz, Germany
  • 4Osservatorio Vesuviano, Istituto Nazionale di Geofisica e Vulcanologia, Napoli, Italy
  • 5Istituto Andaluz de Geofisica, Universidad de Granada, Granada, Spain

The Amatrice (Mw 6.0) - Visso (Mw 5.9) - Norcia (Mw 6.5) seismic sequence (hereafter AVN) struck the Central Apennines (Italy) in 6-7 months during 2016-2017, and it has been widely associated with fluid migration in the normal faults network. The analysis of attenuation parameters (e.g., scattering and absorption) gives information about material properties and the presence of fluids and fracturing. In this study, we investigate in a 3D mapping the scattering contribution to the total attenuation of the AVN seismic sequence (August 2016-January 2017), together with a pre-sequence dataset (March 2013-August 2016). We applied peak delay as a proxy of seismic scattering, to obtain further information on the fracturing processes in time and space. Previous 2D mapping of peak-delay time and coda attenuation tomography in the same study area indicated a substantial control on the scattering of seismic waves by structural (e.g., Monti Sibillini thrust) and lithological (e.g., Umbria- Marche and Lazio-Abruzzi geological domains) features.
Our 3D results show clear differences between the pre-sequence and the sequence, where we can identify an increase of scattering with time after the mainshocks. The substantial alterations in scattering are observed between 4 - 6 km depth, in the hanging wall of the Monti Sibillini thrust, which acts as a rheological barrier between high and low scattering zones. Peak delay variations detected a significant anomaly in the Triassic deposits layer, at the roots of the Acquasanta thrust, east of Monti Sibillini. Here, low scattering during the pre-sequence epoch is replaced by high scattering during the mainshocks. The low scattering along the Acquasanta thrust suggests an increment of pore pressure, associated with the presence of fluids in this geological formation. The subsequent release of those fluids may have caused the mainshocks of the seismic sequence, and a subsequent increase in fracturing, as observed by the high scattering anomaly. These results bring a new light on the importance to consider the thrusts systems in the tectonic framework of the Central Italy.

How to cite: Gabrielli, S., Akinci, A., De Siena, L., Del Pezzo, E., Buttinelli, M., Maesano, F., and Maffucci, R.: The impact of tectonic structures on the 3D scattering imaging of the Central Italy Seismic Sequence, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5861,, 2023.