Intermittent Slip Along the Alto Tiberina Low‐Angle Normal Fault in Central Italy

Vuan, Alessandro; Brondi, Piero; Sugan, M.; Chiaraluce, L.; Stefano, Raffaele Di; Michele, Maddalena

doi:10.1029/2020gl089039

Cited by 17 publications

(14 citation statements)

References 77 publications

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“…The results of the extended catalog can be partially compared with a previous study (Vuan et al, 2020), where the authors applied TM using events nucleating within 1,500 m from the assumed ATF surface to detect ∼16,000 earthquakes within our study period. With the TM approach presented here we are able to detect 32,158 events nucleating in the same fault volume, which is more than twice the number of events detected by Vuan et al (2020). We postulate that the reason for the improved performance in this study is related to the use of a higher frequency band and the higher sampling rate, which allows to better detect small magnitude events.…”

Section: The Extended Seismic Catalogmentioning

confidence: 89%

“…Below 4 km the fault plane is highlighted by micro-seismicity within a 500-1,000 m thick fault zone (Chiaraluce et al, 2007). This micro-seismicity was initially observed at a constant rate (Chiaraluce et al, 2007), while recent research highlighted a variable rate of seismicity along the shallow parts of the LANF, connected with the activity in the HW (Vuan et al, 2020).…”

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confidence: 99%

“…This study revealed a complex mixed mode seismicity (Valoroso et al, 2017). More recently, Vuan et al (2020) used template matching (TM) to better characterize the seismicity adjacent to the LANF surface and found several productive clusters indicating a time intermittent activity rate, indicative of an interaction with M > 3 earthquakes and slow deformation occurring within the HW.…”

mentioning

confidence: 99%

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Spatiotemporal Evolution of the Seismicity in the Alto Tiberina Fault System Revealed by a High‐Resolution Template Matching Catalog

Essing

Poli

2022

JGR Solid Earth

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The Alto Tiberina Fault system, located in the Northern Apennines (Italy), consists of a low angle normal fault (LANF) which radiates micro‐seismicity that can be explained by continuous creep. On top of the LANF, a network of syn‐ and antithetic high angle faults frequently hosts seismic swarms, one of which has been associated with a transient aseismic deformation signal. To study in detail the seismicity and its relationships with aseismic deformation processes occurring in this fault system, we apply template matching on seismic data recorded at an array of borehole stations, to derive a high‐resolution earthquake catalog. Thanks to the additionally detected events, we are able to reveal time periods of increased spatial‐ and temporal clustering during an aseismic deformation event. This reflects the complex evolution of aseismic slip together with the complexity of the shallow fault system. Along the LANF, we observe a bimodal type of seismicity, with diffuse seismicity active continuously, and short‐lived bursts of seismicity that could indicate rapid fluid releases. We additionally identify repeating earthquakes. These events not necessarily match a simple creep model and therefore open the possibility for new models to explain the seismicity along the LANF.

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Section: The Extended Seismic Catalogmentioning

confidence: 89%

mentioning

confidence: 99%

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confidence: 99%

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Spatiotemporal Evolution of the Seismicity in the Alto Tiberina Fault System Revealed by a High‐Resolution Template Matching Catalog

Essing

Poli

2022

JGR Solid Earth

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“…Seismic events were detected by the Italian National Network (ISIDe Working Group, 2007) from the 1st of January 2009 and the 24th of August 2016, the day of the Amatrice mainshock (Figure 1). This starting catalog is then used in a template matching framework (Gibbons & Ringdal, 2006;Sugan et al, 2014Sugan et al, , 2019Vuan et al, 2018Vuan et al, , 2020 to generate an augmented catalog that we used to identify areas with different frictional properties looking at the occurrence over time and space of diverse typologies of clusters (e.g., foreshock-mainshock, mainshock-aftershock, or swarm-like; Zaliapin & Ben-Zion, 2016. Within the events characterized by higher waveforms similarity, we look for repeating earthquakes to be possibly associated with the occurrence of aseismic slip, such as creeping, afterslip, or slow slip events (e.g., Uchida, 2019).…”

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confidence: 99%

The Unlocking Process Leading to the 2016 Central Italy Seismic Sequence

Sugan

Stefano

Chiaraluce

et al. 2023

Geophysical Research Letters

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Approximately 23,000 well-located earthquakes from 2009 to 2016 are used as templates to recover seismic activity preceding the 2016 Central Italy seismic sequence. The resulting spatiotemporal pattern is analyzed by additional ∼91,000 newly detected events. In the 8 years before the sequence onset, seismicity (M L ≤ 3.7) develops at the hangingwall of the 2016 normal faults and along a sub-horizontal shear zone, bounding the active extensional system at depth. This activity, mainly organized in foreshock-mainshock and swarm-like clusters, migrates toward the nucleation area of the first M w 6.0 mainshock of the sequence (24th of August in Amatrice). We propose an unlocking process based on variable temporal clustering of the seismicity, including repeaters, identifying fault portions with different degrees of coupling. Such a progressive localization of the seismic activity at the fault edges induces a weakening of the locked patch of the Amatrice mainshock. Plain Language SummaryWe exploit a high-resolution seismic catalog to describe the activity preceding the 2016 Central Italy sequence. Newly retrieved events are analyzed in space and time to characterize the earthquake preparatory phase leading to the first mainshock of the sequence. Our 8-year-long observations show that most seismic activity involves structures surrounding the nucleation and rupture zone. Interesting seismicity patterns are found along an almost horizontal discontinuity below the upper crustal normal faults and at their northern and southern edges. We highlight migrations, clustering, and progressive seismicity localization close to the first mainshock of the sequence, unveiling a complex preparatory phase.

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“…While seismic data from TABOO reveal release of microseismicity, at a consistently high rate on the ATF fault plane, including repeating earthquakes (RE), no historical earthquake can be unambiguously associated with the activation of the whole ATF [Chiaraluce et al, 2007 and references therein]. REs [Valoroso et al, 2017] together with a steep gradient in crustal velocities [Vadacca et al, 2016], measured by GNSS, and transient surface motion, lasting for few months and coinciding with seismic swarms [Gualandi et al, 2017 andVuan et al, 2020], support the hypothesis that portions of the ATF are creeping aseismically. Recent studies document that any given patch of a fault can creep, nucleate slow earthquakes, and also host large earthquakes [e.g., Iquique earthquake, Ruiz et al, 2014;Tohoku earthquake, Kato et al, 2012 andParkfield, Veedu andBarbot, 2016].…”

Section: The Alto Tiberina Near Fault Observatory (Taboo)mentioning

confidence: 99%

The Near Fault Observatory community in Europe: a new resource for faulting and hazard studies

Chiaraluce

Festa²,

Bernard³

et al. 2022

Annals of Geophysics

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The Near Fault Observatories (NFOs) community is one of the European Plate Observing System (EPOS, http://www.epos-eu.org) Thematic Communities, today consisting of six research infrastructures that operate in regions characterised by high seismic hazard originating from different tectonic regimes. Earthquakes respond to complex natural systems whose mechanical properties evolve over time. Thus, in order to understand the multi-scale, physical/chemical processes responsible for the faulting that earthquakes occur on, it is required to consider phenomena that intersect different research fields, i.e., to put in place multidisciplinary monitoring. Hence, NFOs are grounded on modern and multidisciplinary infrastructures, collecting near fault high resolution raw data that allows generation of innovative scientific products. The NFOs usually complement regional backbone networks with a higher density distribution of seismic, geodetic, geochemical and other geophysical sensors, at surface and sometimes below grade. These dense and modern networks of multi-parametric sensors are sited at and around active faults, where moderate to large earthquakes have occurred in the past and are expected in the future. They continuously monitor the underlying Earth instability processes over a broad time interval. Data collected at each NFO results in an exceptionally high degree of knowledge of the geometry and parameters characterizing the local geological faults and their deformation pattern. The novel data produced by the NFO community is aggregated in EPOS and is made available to a diverse set of stakeholders through the NFO Federated Specific Data Gateway (FRIDGE). In the broader domain of the Solid Earth sciences, NFOs meet the growing expectations of the learning and communication sectors by hosting a large variety of scientific information about earthquakes as a natural phenomenon and a societal issue. It represents the EPOS concept and objective of aggregating and harmonising the European research infrastructures capabilities to facilitate broader scientific opportunity. The NFOs are at the cutting edge of network monitoring. They conduct multidisciplinary experiments for testing multi-sensor stations, as well as realise robust and ultra-low latency, transmission systems that can routinely accommodate temporary monitoring densification. The effort to continuously upgrade the technological efficiency of monitoring systems positions the NFO at the centre of marketing opportunities for the European enterprises devoted to new sensor technology. The NFOs constitute ideal test beds for generating expertise on data integration, creating tools for the next generation of multidisciplinary research, routine data analysis and data visualization. In particular focus is often on near-real time tools and triggering alarms at different levels are tested and implemented, strengthening the cooperation with the Agencies for risk management. NFOs have developed innovative operational actions such as the Testing Centre for Earthquake Early Warning and Source Characterisation (CREW) and detailed fast ground shaking and damage characterization. Complementing the recent growth of modern laboratory and computational models, the NFOs can provide interdisciplinary observations of comparable high resolution to describe the behaviour of fault slip over a vast range of spatial and temporal scales and aiding to provide more accurate earthquake hazard characterizations.

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Intermittent Slip Along the Alto Tiberina Low‐Angle Normal Fault in Central Italy

Cited by 17 publications

References 77 publications

Spatiotemporal Evolution of the Seismicity in the Alto Tiberina Fault System Revealed by a High‐Resolution Template Matching Catalog

Spatiotemporal Evolution of the Seismicity in the Alto Tiberina Fault System Revealed by a High‐Resolution Template Matching Catalog

The Unlocking Process Leading to the 2016 Central Italy Seismic Sequence

The Near Fault Observatory community in Europe: a new resource for faulting and hazard studies

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