Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence
The Amatrice–Visso–Norcia seismic sequence struck Central Italy across the Apenninic normal fault system in 2016. Fluids likely triggered the sequence and reduced the stability of the fault network following the first earthquake (Amatrice, Mw 6.0), with their migration nucleating the Visso (Mw 5.9)...
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Frontiers Media S.A.
2022-06-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2022.909698/full |
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| author | Simona Gabrielli Simona Gabrielli Aybige Akinci Guido Ventura Ferdinando Napolitano Edoardo Del Pezzo Edoardo Del Pezzo Luca De Siena Luca De Siena |
| author_facet | Simona Gabrielli Simona Gabrielli Aybige Akinci Guido Ventura Ferdinando Napolitano Edoardo Del Pezzo Edoardo Del Pezzo Luca De Siena Luca De Siena |
| author_sort | Simona Gabrielli |
| collection | DOAJ |
| description | The Amatrice–Visso–Norcia seismic sequence struck Central Italy across the Apenninic normal fault system in 2016. Fluids likely triggered the sequence and reduced the stability of the fault network following the first earthquake (Amatrice, Mw 6.0), with their migration nucleating the Visso (Mw 5.9) and Norcia (Mw 6.5) mainshocks. However, both spatial extent and mechanisms of fluid migration and diffusion through the network remain unclear. High fluid content, enhanced permeability, and pervasive microcracking increase seismic attenuation, but different processes contribute to different attenuation mechanisms. Here, we measured and mapped peak delay time and coda attenuation, using them as proxies of seismic scattering and absorption before and during the sequence. We observed that the structural discontinuities and lithology control the scattering losses at all frequencies, with the highest scattering delineating carbonate formations within the Gran Sasso massif. The Monti Sibillini thrust marks the strongest contrasts in scattering, indicating a barrier for northward fracture propagation. Absorption does not show any sensitivity to the presence of these main geological structures. Before the sequence, low-frequency high-absorption anomalies distribute around the NW-SE-oriented Apennine Mountain chain. During the sequence, a high-absorption anomaly develops from SSE to NNW across the seismogenic zone but remains bounded north by the Monti Sibillini thrust. We attribute this spatial expansion to the deep migration of CO2-bearing fluids across the strike of the fault network from a deep source of trapped CO2 close to the Amatrice earthquake. Fluids expand SSE-NNW primarily during the Visso sequence and then diffuse across the fault zones during the Norcia sequence. |
| first_indexed | 2024-12-12T08:03:56Z |
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| id | doaj.art-7a934afb4340413b8d7fb54c08a5e8a1 |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-12T08:03:56Z |
| publishDate | 2022-06-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-7a934afb4340413b8d7fb54c08a5e8a12022-12-22T00:32:02ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632022-06-011010.3389/feart.2022.909698909698Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic SequenceSimona Gabrielli0Simona Gabrielli1Aybige Akinci2Guido Ventura3Ferdinando Napolitano4Edoardo Del Pezzo5Edoardo Del Pezzo6Luca De Siena7Luca De Siena8Istituto Nazionale di Geofisica e Vulcanologia, Rome, ItalySchool of Geosciences, University of Aberdeen, Aberdeen, United KingdomIstituto Nazionale di Geofisica e Vulcanologia, Rome, ItalyIstituto Nazionale di Geofisica e Vulcanologia, Rome, ItalyDipartimento di Fisica “E.R. Caianiello”, Università degli Studi di Salerno, Fisciano, ItalyOsservatorio Vesuviano, Istituto Nazionale di Geofisica e Vulcanologia, Napoli, ItalyIstituto Andaluz de Geofisica, Universidad de Granada, Granada, SpainSchool of Geosciences, University of Aberdeen, Aberdeen, United KingdomInstitute of Geosciences, Johannes Gutenberg University, University of Mainz, Mainz, GermanyThe Amatrice–Visso–Norcia seismic sequence struck Central Italy across the Apenninic normal fault system in 2016. Fluids likely triggered the sequence and reduced the stability of the fault network following the first earthquake (Amatrice, Mw 6.0), with their migration nucleating the Visso (Mw 5.9) and Norcia (Mw 6.5) mainshocks. However, both spatial extent and mechanisms of fluid migration and diffusion through the network remain unclear. High fluid content, enhanced permeability, and pervasive microcracking increase seismic attenuation, but different processes contribute to different attenuation mechanisms. Here, we measured and mapped peak delay time and coda attenuation, using them as proxies of seismic scattering and absorption before and during the sequence. We observed that the structural discontinuities and lithology control the scattering losses at all frequencies, with the highest scattering delineating carbonate formations within the Gran Sasso massif. The Monti Sibillini thrust marks the strongest contrasts in scattering, indicating a barrier for northward fracture propagation. Absorption does not show any sensitivity to the presence of these main geological structures. Before the sequence, low-frequency high-absorption anomalies distribute around the NW-SE-oriented Apennine Mountain chain. During the sequence, a high-absorption anomaly develops from SSE to NNW across the seismogenic zone but remains bounded north by the Monti Sibillini thrust. We attribute this spatial expansion to the deep migration of CO2-bearing fluids across the strike of the fault network from a deep source of trapped CO2 close to the Amatrice earthquake. Fluids expand SSE-NNW primarily during the Visso sequence and then diffuse across the fault zones during the Norcia sequence.https://www.frontiersin.org/articles/10.3389/feart.2022.909698/fullseismic attenuationscatteringfluidearthquake sequenceCentral Italy |
| spellingShingle | Simona Gabrielli Simona Gabrielli Aybige Akinci Guido Ventura Ferdinando Napolitano Edoardo Del Pezzo Edoardo Del Pezzo Luca De Siena Luca De Siena Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence Frontiers in Earth Science seismic attenuation scattering fluid earthquake sequence Central Italy |
| title | Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence |
| title_full | Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence |
| title_fullStr | Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence |
| title_full_unstemmed | Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence |
| title_short | Fast Changes in Seismic Attenuation of the Upper Crust due to Fracturing and Fluid Migration: The 2016–2017 Central Italy Seismic Sequence |
| title_sort | fast changes in seismic attenuation of the upper crust due to fracturing and fluid migration the 2016 2017 central italy seismic sequence |
| topic | seismic attenuation scattering fluid earthquake sequence Central Italy |
| url | https://www.frontiersin.org/articles/10.3389/feart.2022.909698/full |
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