← Back to Sessions

3D Mapping of Scattering Attenuation for the Central Italy 2016-2017 Seismic Sequence

Description: 

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), which has been associated with fluid circulation in the normal fault network. Seismic attenuation parameters (e.g., scattering and absorption) are powerful tools for detecting fluid presence and fracturing. The aim of this work is to investigate with 3D images, in space and time, the scattering contribution to the total attenuation of two datasets, one before the mainshock of Amatrice (March 2013-August 2016) and a second during the sequence (August 2016-January 2017). To measure scattering, we used peak delay mapping.
A comparison between the 3D mapping of the pre-sequence and sequence shows a dissimilarity in scattering, with a general increase of it over time after the Amatrice main event. Main structural elements (e.g., Monti Sibillini and Acquasanta thrusts) and lithologies are strongly controlling the scattering losses, with changes from low to high scattering around 4 and 6 km depth, west of the Norcia basin and of the Monti Sibillini thrust, suggesting an increment of fracturing due to the intense seismic activity. Monti Sibillini and Acquasanta thrusts act also as rheological barriers, creating contact between different geological domains. This causes a scattering contrast due to different responses in fracturing and compacting before and during the seismic sequence. Low scattering anomalies are located at the footwall of the thrusts during a pre-sequence phase, replaced by high scattering after the mainshocks. Low scattering can be associated with increased pore pressure due to fluid circulation in Triassic deposit layers; the movement and release of the pressure starting from this formation possibly provoked the movement of the thrusts, triggering the main events of the 2016 sequence.

Session: Crustal Imaging of High Seismic Hazard Regions

Type: Oral

Date: 4/20/2023

Presentation Time: 10:15 AM (local time)

Presenting Author: Simona Gabrielli

Student Presenter: No

Invited Presentation: 

Authors