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  • Articles  (21)
  • Oxford University Press - The Royal Astronomical Society  (20)
  • American Chemical Society
  • American Institute of Physics (AIP)
  • 2020-2024  (21)
  • 1965-1969
  • 2023  (21)
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  • Articles  (21)
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  • 2020-2024  (21)
  • 1965-1969
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  • 1
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    3-D shear wave velocity model of the lithosphere below the Sardinia–Corsica continental block based on Rayleigh-wave phase velocities (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-10-25
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2020. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: Rayleigh-wave dispersion curves from both ambient noise and teleseismic events allow us to provide the first high-resolution 3-D shear wave velocity (VS) model of the crust and upper mantle below the Sardinia–Corsica microplate, an important continental block for understanding the evolution of the central-western Mediterranean. For a wide range of periods (from 3 to ∼30 s), the phase velocities of the study area are systematically higher than those measured within the Italian peninsula, in agreement with a colder geotherm. Relative and absolute variations in the VS allow us to detect a very heterogeneous upper crust down to 8 km, as opposed to a relatively homogeneous middle and lower crust. The isosurface at 4.1 km s−1 is consistent with a rather flat Moho at a depth of 28.0 ± 1.8 km (2σ). The lithospheric mantle is relatively cold, and we constrain the thermal lithosphere–asthenosphere boundary at ∼100 km. We find our estimate consistent with a continental geotherm based on a surface heat flow of 60 mW m−2. Our results suggest that most of the lithosphere endured the complex history of deformation experienced by the study area and imply, in general, that deep tectonic processes do not easily destabilize the deeper portion of the continental lithosphere, despite leaving a clear surface signature.
    Description: Published
    Description: 2119–2130
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    Reproducing complex anisotropy patterns at subduction zones from splitting intensity analysis and anisotropy tomography (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-11-13
    Description: Measurements of seismic anisotropy provide a lot of information on the deformation and structure as well as flows of the Earth’s interior, in particular of the upper mantle. Even though the strong and heterogeneous seismic anisotropic nature of the upper mantle has been demon- strated by a wealth of theoretical and observational approaches , most of standard teleseismic body-wave tomography studies overlook P- and S-wave anisotropy, thus producing artefacts in tomographic models in terms of amplitude and localization of heterogeneities. Conven- tional methods of seismic anisotropy measurement have their limitations regarding lateral and mainly depth resolution. To overcome this problem much effort has been done to develop tomographic methods to invert shear wave splitting data for anisotropic structures, based on finite-frequency sensitivity kernels that relate model perturbations to splitting observations. A promising approach to image the upper mantle anisotropy is the inversion of splitting intensity (SI). This seismic observable is a measure of the amount of energy on the transverse component waveform and, to a first order, it is linearly related to the elastic perturbations of the medium through the 3-D sensitivity kernels, that can be therefore inverted, allowing a high-resolution image of the upper mantle anisotropy. Here we present an application of the SI tomography to a synthetic subduction setting. Starting from synthetic SKS waveforms, we first derived high-quality SKS SI measurements; then we used the SI data as input into tomographic inver- sion. This approach enables high-resolution tomographic images of upper-mantle anisotropy through recovering vertical and lateral changes in anisotropy and represents a propaedeutic step to the real cases of subduction settings. Additionally this study was able to detect regions of strong dipping anisotropy by allowing a 360◦ periodic dependence of the splitting vector.
    Description: NEWTON (NEw Window inTO Earth’s iNterior), ERC StG funded project (grant ID:758199) INGV Pianeta Dinamico 2021–2022 Tema 4 KINDLE (grant no. CUP D53J19000170001)
    Description: Published
    Description: 1725–1735
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Keywords: Seismic anisotropy, slab modelling ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    The Moho reflectivity of the subduction beneath the Southwestern Alps from ambient seismic noise autocorrelations (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-02-21
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2022. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: The Western Alps shows a complex crustal organization due to the subduction of the European Plate beneath the Adriatic Plate and exhumation of the mantle wedge. The lithospheric structure of the Western Alps, that may hold significance for understanding orogenic processes and evolution, has been the subject of many geophysical studies, but the Moho profile remains unclear and this has led to controversies about the depth and extent of the European Plate beneath the Adriatic Plate. With the goal of retrieving detailed information on crustal constitution, we use autocorrelation of seismic ambient noise as a tool to map the body wave reflectivity structure at the subduction zone under the southwestern Alps. We use data recorded by the China–Italy–France Alps (CIFALPS) seismic transect, that includes 45 stations located approximately 5–10 km apart along a profile crossing the Alpine continental subduction in the Western Alps. We analyse the data set in four different frequency bands between 0.09 and 2 Hz. We automatically pick the arrival time of the Moho reflection in the second derivative of the envelope of the autocorrelation stack using prior Moho information. The 0.5–1 Hz frequency band mostly gives the best result due to the clear changes in reflectivity along the waveforms of the autocorrelation stacks after the picked arrival times of the Moho reflections. We find spatial coherence between 18 and 23 km depth in the western portion of the profile, indicating relatively homogeneous crustal rocks, and highly reflective structure under the central mountain range, due to the existence of a highly faulted zone. The very thin crust and the underlying mantle wedge known as the Ivrea body show instead high transparency to seismic waves and absence of reflections. The subduction profile of the European Plate shows a steep trend as compared to previous studies. We discuss autocorrelation stacks and Moho depths obtained from the arrival times of the picked reflectivity change in comparison with previous studies to validate the different reflection structures. Stacked ambient noise autocorrelations reliably image varied crustal properties and reflectivity structures in the highly heterogeneous region of the southwestern Alps.
    Description: Published
    Description: 298–316
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Europe ; Body waves ; Seismic Interferometry ; Seismic noise ; Crustal structure ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    The AlpArray Research Seismicity-Catalogue (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-02-21
    Description: We take advantage of the new large AlpArray Seismic Network (AASN) as part of the AlpArray research initiative (www.alparray.ethz.ch), to establish a consistent seismicity-catalogue for the greater Alpine region (GAR) for the time period 2016 January 1–2019 December 31. We use data from 1103 stations including the AASN backbone composed of 352 permanent and 276 (including 30 OBS) temporary broad-band stations (network code Z3). Although characterized by a moderate seismic hazard, the European Alps and surrounding regions have a higher seismic risk due to the higher concentration of values and people. For these reasons, the GAR seismicity is monitored and routinely reported in catalogues by a 11 national and 2 regional seismic observatories. The heterogeneity of these data set limits the possibility of extracting consistent information by simply merging to investigate the GAR's seismicity as a whole. The uniformly spaced and dense AASN provides, for the first time, a unique opportunity to calculate high-precision hypocentre locations and consistent magnitude estimation with uniformity and equal uncertainty across the GAR. We present a new, multistep, semi-automatic method to process ∼50 TB of seismic signals, combining three different software. We used the SeisComP3 for the initial earthquake detection, a newly developed Python library ADAPT for high-quality re-picking, and the well-established VELEST algorithm both for filtering and final location purposes. Moreover, we computed new local magnitudes based on the final high-precision hypocentre locations and re-evaluation of the amplitude observations. The final catalogue contains 3293 seismic events and is complete down to local magnitude 2.4 and regionally consistent with the magnitude 3+ of national catalogues for the same time period. Despite covering only 4 yr of seismicity, our catalogue evidences the main fault systems and orogens’ front in the region, that are documented as seismically active by the EPOS-EMSC manually revised regional bulletin for the same time period. Additionally, we jointly inverted for a new regional minimum 1-D P-wave velocity model for the GAR and station delays for both permanent station networks and temporary arrays. These results provide the base for a future re-evaluation of the past decades of seismicity, and for the future seismicity, eventually improving seismic-hazard studies in the region. Moreover, we provide a unique, consistent seismic data set fundamental to further investigate this complex and seismically active area. The catalogue, the minimum 1-D P-wave velocity model, and station delays associated are openly shared and distributed with a permanent DOI listed in the data availability section.
    Description: The AlpArray-Switzerland project is funded by the Swiss-AlpArray SINERGIA project CRSII2_154434/1 by Swiss National Science Foundation (SNSF).
    Description: Published
    Description: 921-943
    Description: 1T. Struttura della Terra
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: Earthquake source observations ; Seismicity ; Tectonics ; Statistical seismology ; 04.06. Seismology ; 04.01. Earth Interior
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Surface-wave tomography using SeisLib: a Python package for multiscale seismic imaging (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-02-21
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2022. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: To improve our understanding of the Earth’s interior, seismologists often have to deal with enormous amounts of data, requiring automatic tools for their analyses. It is the purpose of this study to present SeisLib, an open-source Python package for multiscale seismic imaging. At present, SeisLib includes routines for carrying out surface-wave tomography tasks based on seismic ambient noise and teleseismic earthquakes. We illustrate here these functionalities, both from the theoretical and algorithmic point of view and by application of our library to seismic data from North America. We first show how SeisLib retrieves surface-wave phase velocities from the ambient noise recorded at pairs of receivers, based on the zero crossings of their normalized cross-spectrum. We then present our implementation of the two-station method, to measure phase velocities from pairs of receivers approximately lying on the same great-circle path as the epicentre of distant earthquakes. We apply these methods to calcu- late dispersion curves across the conterminous United States, using continuous seismograms from the transportable component of USArray and earthquake recordings from the permanent networks. Overall, we measure 144 272 ambient-noise and 2055 earthquake-based dispersion curves, that we invert for Rayleigh-wave phase-velocity maps. To map the lateral variations in surface-wave velocity, SeisLib exploits a least-squares inversion algorithm based on ray theory. Our implementation supports both equal-area and adaptive parametrizations, with the latter al- lowing for a finer resolution in the areas characterized by high density of measurements. In the broad period range 4–100 s, the retrieved velocity maps of North America are highly correlated (on average, 96 per cent) and present very small average differences (0.14 ± 0.1 per cent) with those reported in the literature. This points to the robustness of our algorithms. We also produce a global phase-velocity map at the period of 40 s, combining our dispersion measurements with those collected at global scale in previous studies. This allows us to demonstrate the reliability and optimized computational speed of SeisLib, even in presence of very large seismic inverse problems and strong variability in the data coverage. The last part of the manuscript deals with the attenuation of Rayleigh waves, which can be estimated through SeisLib based on the seismic ambient noise recorded at dense arrays of receivers. We apply our algorithm to produce an at- tenuation map of the United States at the period of 4 s, which we find consistent with the relevant literature.
    Description: Funded by the Deutsche Forschungsgemeinschaft (DFG - German Research Foundation) under the Individual Research Project: SI 1748/4- 1. German Science Foundation: Deutsche Forschungsgemeinschaft (www.dfg.de; SPP-2017, Project Ha 2403/21-1).
    Description: Published
    Description: 1011-1030
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Inverse theory ; Seismic tomography ; Surface waves ; free oscillations ; 04.01. Earth Interior ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Seismic source mapping by surface wave time reversal: application to the great 2004 Sumatra earthquake (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-02-21
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2023. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: Different approaches to map seismic rupture in space and time often lead to incoherent results for the same event. Building on earlier work by our team, we ‘time-reverse’ and ‘backpropagate’ seismic surface wave recordings to study the focusing of the time-reversed field at the seismic source. Currently used source-imaging methods relying on seismic recordings neglect the information carried by surface waves, and mostly focus on the P-wave arrival alone. Our new method combines seismic time reversal approach with a surface wave ray-tracing algorithm based on a generalized spherical-harmonic parametrization of surface wave phase velocity, accounting for azimuthal anisotropy. It is applied to surface wave signal filtered within narrow-frequency bands, so that the inherently 3-D problem of simulating surface wave propagation is separated into a suite of 2-D problems, each of relatively limited computational cost. We validate our method through a number of synthetic tests, then apply it to the great 2004 Sumatra–Andaman earthquake, characterized by the extremely large extent of the ruptured fault. Many studies have estimated its rupture characteristics from seismological data (e.g. Lomax, Ni et al., Guilbert et al., Ishii et al., Krüger & Ohrnberger, Jaffe et al.) and geodetic data (e.g. Banerjee et al., Catherine et al., Vigny et al., Hashimoto et al., Bletery et al.). Applying our technique to recordings from only 89 stations of the Global Seismographic Network (GSN) and bandpass filtering the corresponding surface wave signal around 80-to-120, 50-to-110 and 40-to-90 s, we reproduce the findings of earlier studies, including in particular the northward direction of rupture propagation, its approximate spatial extent and duration, and the locations of the areas where most energy appears to be released.
    Description: Published
    Description: 1018-1035
    Description: 1T. Struttura della Terra
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: Earthquake source observations ; Surface waves and free oscillations ; Theoretical seismology ; Wave propagation ; 04.06. Seismology ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Active tectonics and fault evolution in the Western Balkans (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-01-16
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2022. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy. All rights reserved.
    Description: The western Balkans occupy a region influenced by two major active tectonic processes: the collision between the Adriatic Region and the Dinarides in the west, and the extension of the Aegean Region and its surroundings as they move towards the Hellenic Trench. An understanding of the kinematics and dynamics of the western Balkans has significance for our understanding of continental tectonics in general, and is the object of this paper. The region is rich in observational data, with many well-studied earthquakes, good geodetic coverage by GNSS (Global Navigation Satellite System) and abundant exposure of active faulting and its associated geomorphology, especially within the Mesozoic carbonates that cover large sectors of the extensional areas. We first use such observations to establish the regional kinematic patterns, by which we mean a clarification of how active faulting achieves the motions observed in the deforming velocity field obtained from GNSS measurements. We then use geomorphological observations on the evolution of drainage systems to establish how kinematic and faulting patterns have changed and migrated during the Late Neogene-Quaternary. The kinematics, and its evolution, can then be used to infer characteristics of the dynamics, by which we mean the origin and effect of the forces that control the overall deformation. The principal influences are: (i) the distribution and evolution of gravitational potential energy (GPE) contrasts arising from crustal thickness variations and elevation, in particular the growth of topography by shortening in the Albanides–Hellenides mountain ranges and the high elevation of mainland Greece relative to the Mediterranean seafloor and (ii) the ability of the boundaries of the region, along the Adriatic coast and in the Hellenic Trench, to support the forces arising from those GPE contrasts. The evolution in space and time indicates an interaction between the anisotropic strength fabric of the upper crust associated with faulting, and the more distributed and smoother patterns of flow that are likely to characterize the ductile deformation of the lower, aseismic part of the lithosphere—both of which influence the deformation on the scale of 100–200 km. The persistent argument about whether continental deformation is best described by a continuum or by rigid-block motions is largely a matter of scale and particular location: both are influential in establishing the patterns we see.
    Description: Published
    Description: 2102–2126
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Rock magnetic fingerprint of Mt Etna volcanic ash (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-01-16
    Description: This article has been accepted for publication in Geophysical Journal International ©:The Author(s) 2022. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Uploaded in accordance with the publisher's self-archiving policy.
    Description: A detailed rock magnetic study was conducted on ash samples collected from different products erupted during explosive activity of Mount Etna, Italy, in order to test the use of magnetic properties as discriminating factors among them, and their explosive character in particular. Samples include tephra emplaced during the last 18 ka: the benmoreitic Plinian eruptions of the Pleistocene Ellittico activity from marine core ET97-70 (Ionian Sea) and the basaltic Holocene FG eruption (122 BC), the Strombolian/Phreatomagmatic/sub-Plinian eruptions (namely, the Holocene TV, FS, FL, ETP products and the 1990, 1998 eruptions) collected from the slope of the volcano, and the Recent explosive activity (lava fountains referred to as ‘Ash Rich Jets and Plumes’, or ARJP) that occurred in the 2001–2002 period, related to flank eruptions. Mössbauer spectrometry informs that a single magnetic mineral dominates the three groups, which are characterized by variable magnetic grain sizes and composition. Detailed rock-magnetic investigations, ranging from low temperature to high temperature remanence and susceptibility experiments, indicate that the more explosive products of the Plinian eruptions and ARJP activity tephra, are characterized by oxidized Ti-rich titanomagnetites, with dominant Curie Temperatures between 230 and 330 °C. The FG and ARJP tephra are also characterized by contrasting, yet overall higher, coercivity distributions and higher magnetizations and susceptibilities, including below room temperature. In contrast, most of the Strombolian/sub-Plinian eruptions have a magnetic signature dominated by less coercive magnetite and/or Ti-poor titanomagnetite. Magnetic differences observed between the Late Pleistocene and Holocene FG Plinian eruptions can be attributed to the different composition of the former eruptions, which were fed by more evolved magmas, whereas geochemical variations characterizing the products erupted in the last few decades can be responsible for the differences between the Holocene and recent Strombolian/sub-Plinian products. Importantly, detailed magnetic investigation of sideromelane and tachylite clasts, the two end members of the juvenile fraction extracted from the ash of the most explosive products, determines that the tachylite fraction is responsible for the magnetic signature of the Plinian FG and ARJP tephra, and is attributed to the intense fragmentation that characterizes these activities, likely resulting from undercooling processes. Moreover, the abundant superparamagnetic grains associated with these eruptive styles are believed to represent the nanolite fraction responsible for the increasing viscosity of these magmas, and to be responsible for their explosive character. The distinctive magnetic properties that characterize the tachylite-bearing tephra, representative of the fragmentation process that distinguishes the most explosive activities, provides a useful magnetic tool that can complement traditional volcanological investigations.
    Description: Published
    Description: 749–769
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Superparamagnetic Iron Oxide Nanoparticle Nanodevices Based on Fe3O4 Coated by Megluminic Ligands for the Adsorption of Metal Anions from Water (2023)
    American Chemical Society
    Details
    Publication Date: 2023-01-16
    Description: The uptake ability toward arsenic(V), chromium(VI), and boron(III) ions of ad hoc functionalized magnetic nanostructured devices has been investigated. To this purpose, ligands based on meglumine have been synthesized and used to coat magnetite nanoparticles (Fe3O4) obtained by the co-precipitation methodology. The as-prepared hybrid material was characterized by infrared spectroscopy (IR), X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy combined with energy-dispersive X-ray analysis. Moreover, its magnetic hysteresis properties were measured to evaluate its magnetic properties, and the adsorption kinetics and isothermal models were applied to discern between the different adsorption phenomena. Specifically, the better fitting was observed by the Langmuir isotherm model for all metal ions tested, highlighting a higher uptake in arsenic (28.2 mg/g), chromium (12.3 mg/g), and boron (23.7 mg/g) sorption values if compared with other magnetic nanostructured materials. After adsorption, an external magnetic stimulus can be used to efficiently remove nanomaterials from the water. Finally the nanomaterial can be reused up to five cycles and regenerated for another three cycles.
    Description: Published
    Description: 10775–10788
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Frictional properties of Opalinus Clay: influence of humidity, normal stress and grain size on frictional stability (2023)
    Oxford University Press - The Royal Astronomical Society
    Details
    Publication Date: 2023-02-01
    Description: The Opalinus Clay (OPA) is a clay-rich formation considered as a potential host rock for radioactive waste repositories and as a caprock for carbon storage in Switzerland. Its very low permeability (10−19 to 10−21 m2) makes it a potential sealing horizon, however the presence of faults that may be activated during the lifetime of a repository project can compromise the long-term hydrological confinement, and lead to mechanical instability. Here, we have performed laboratory experiments to test the effect of relative humidity (RH), grain size (g.s.) and normal stress on rate-and-state frictional properties and stability of fault laboratory analogues corresponding to powders of OPA shaly facies. The sifted host rock powders at different grain size fractions (〈63 μm and 63 〈 g.s. 〈 125 μm), at room (∼25 per cent) and 100 per cent humidity, were slid in double-direct shear configuration, under different normal stresses (5–70 MPa). We observe that peak friction, μpeak and steady-state friction, μss, depend on water vapour content and applied normal stress. Increasing relative humidity from ∼25 per cent RH (room humidity) to 100 per cent RH causes a decrease of frictional coefficient from 0.41 to 0.35. The analysis of velocity-steps in the light of rate-and-state friction framework shows that the stability parameter (a–b) is always positive (velocity-strengthening), and it increases with increasing sliding velocity and humidity. The dependence of (a–b) on slip rate is lost as normal stress increases, for each humidity condition. By monitoring the variations of the layer thickness during the velocity steps, we observe that dilation (Δh) is directly proportional to the sliding velocity, decreases with normal stress and is unaffected by humidity. Microstructural analysis shows that most of the deformation is accommodated within B-shear zones, and the increase of normal stress (σn) promotes the transition from strain localization and grain size reduction to distributed deformation on a well-developed phyllosilicate network. These results suggest that: (1) the progressive loss of velocity dependence of frictional stability parameter (a–b) at σn > 35 MPa is dictated by a transition from localized to distributed deformation and (2) water vapour content does not affect the deformation mechanisms and dilation, whereas it decreases steady-state friction (μss), and enhances fault stability.
    Description: Published
    Description: 211–228
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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