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  • 1
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    The tectonic puzzle of the Messina area (Southern Italy): Insights from new seismic reflection data (2012)
    Nature Publishing Group
    In:  Scientific Reports, 2 . p. 970.
    Details
    Publication Date: 2015-06-24
    Description: The Messina Strait, that separates peninsular Italy from Sicily, is one of the most seismically active areas of the Mediterranean. The structure and seismotectonic setting of the region are poorly understood, although the area is highly populated and important infrastructures are planned there. New seismic reflection data have identified a number of faults, as well as a crustal scale NE-trending anticline few km north of the strait. These features are interpreted as due to active right-lateral transpression along the north-eastern Sicilian offshore, coexisting with extensional and right-lateral transtensional tectonics in the southern Messina Strait. This complex tectonic network appears to be controlled by independent and overlapping tectonic settings, due to the presence of a diffuse transfer zone between the SE-ward retreating Calabria subduction zone relative to slab advance in the western Sicilian side.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1038/srep00970
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Jurassic rifting evolution of the Apennines and Southern Alps (Italy): Parallels and differences (2011)
    Geological Society of America (GSA)
    Details
    Publication Date: 2011-03-01
    Description: Jurassic rifting in the Southern Alps and Northern Apennines occurred within a relatively short (2-4 m.y.) interval of tectonic activity (late Hettangian-early Sinemurian) in proximal areas (central-eastern Southern Alps and Northern Apennines), and was followed by calm postrift sedimentation. The main axis of the rift jumped in the late Early Jurassic to the previously unaffected, mostly nonsubsiding and/or uplifted distal areas of southwestern Tuscany and the western Southern Alps. Synchronous stretching occurred in the Helvetic-Brianconnais domains of the Alps and in the Longobucco-Caloveto area (Calabria), here interpreted as the conjugate margin of western Southern Alps and southwestern Tuscany. Major differences occur in the extensional structural style of the Southern Alps and Apennines. The Northern Apennines are characterized by diffuse thin-skinned stretching at shallow depths and by localized thick-skinned stretching at deeper crustal levels. This style contrasts with the well-known thick-skinned nature of extensional tectonics in the Southern Alps, which are also characterized by a larger spacing between major normal faults. It is suggested that these different extensional styles were controlled by contrasting rheologies induced by the different stratigraphies. The strong strain partitioning and the diffuse shallow thin-skinned tectonics of the Northern Apennines basins are here related to the occurrence of thick (up to 2 km) evaporites that underlie a relatively thin (up to 1.3 km) carbonate platform.
    Print ISSN: 0016-7606
    Electronic ISSN: 1943-2674
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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    PAPER CURRENT
  • 3
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    Numerical analysis of interseismic, coseismic and postseismic phases for normal and reverse faulting earthquakes in Italy (2021)
    Oxford University Press
    Details
    Publication Date: 2021-02-23
    Description: The preparation, initiation, and occurrence dynamics of earthquakes in Italy are governed by several frequently unknown physical mechanisms and parameters. Understanding these mechanisms is crucial for developing new techniques and approaches for earthquake monitoring and hazard assessments. Here, we develop a first-order numerical model simulating quasi-static crustal interseismic loading, coseismic brittle episodic dislocations, and postseismic relaxation for extensional and compressional earthquakes in Italy based on a common framework of lithostatic and tectonic forces. Our model includes an upper crust, where the fault is locked, and a deep crust, where the fault experiences steady shear.
    Description: Published
    Description: 627–645
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Active Fold‐Thrust Belt to Foreland Transition in Northern Adria, Italy, Tracked by Seismic Reflection Profiles and GPS Offshore Data (2020)
    Wiley Agu
    Details
    Publication Date: 2020-12-15
    Description: The Adria microplate is the foreland of the oppositely verging Apennines and Alps or Dinarides fold‐thrust belts associated to the related subduction zones. Along its western margin, the Adria plate hosts the active Northern Apennines accretionary prism, which is buried under the Adriatic Sea and the Po Plain. The interpretation of seismic reflection profiles and borehole data allowed us to define the geometry of the transition from the Apennines fold‐thrust belt to its undeformed foreland. Moreover, continuous GPS (CGPS) data from offshore hydrocarbon platforms anchored to the seabed of the northern Adriatic plate allow to measure present‐day kinematics. Although the CGPS signals are affected by non‐tectonic components associated with hydrocarbon extraction, the integration of geodetic analysis, subsurface geological reconstructions, and analytical modeling allowed us to constrain the ongoing tectonic activity. Shortening is currently accommodated by aseismic slip along the basal detachment, likely accumulating elastic energy along the frontal ramp that may eventually seismically slip. Our multidisciplinary study suggests that the study area may not be sheltered from relevant seismic sequences similar to the Mw 6 Emilia 2012 events and that the occurrence of potential seismogenic sources in the area should be carefully evaluated. Similar studies may be useful to constrain the present‐day activity in other marine areas and to identify potential and hitherto unrecognized seismogenic sources along the entire Apennines belt and other accretionary prisms worldwide.
    Description: Published
    Description: e2020TC006425
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Lithological control on multiple surface ruptures during the 2016–2017 Amatrice-Norcia seismic sequence (2020)
    Details
    Publication Date: 2020-02-06
    Description: On August 24th 2016, a Mw 6.0 earthquake started the Amatrice - Norcia (Central Italy) seismic sequence, generated by the extensional tectonics along the Apennines, that had its apex with the Mw 6.5 October 30th mainshock. As a unique documented case reported in Italy, complex surface faulting occurred during both earthquakes along the Mt. Vettore fault. Multiple surface faulting was accompanied at depth by the development of a km-scale normal fault-propagation fold. This fold was characterized by breakthrough and by surface rupture within thick carbonatic layers only in the central and north-western area (Mt. Vettore). On the contrary, the fault remained blind where flexural slip was active in sandy-silty turbiditic deposits in the south-eastern area (Mt. Gorzano). We explain the different faulting behaviour with the occurrence of more rigid and competent lithologies in areas characterized by breakthrough and with the occurrence of weaker lithologies in areas characterized by blind faulting. Overall, the entire seismic sequence appears as a gradual gravitational adjustment of the hangingwall block, slipping along a NW-trending and 80 km long fault system. In particular, the following crustal blocks, partially overlapping and with different length (30, 40 and 22 km, respectively), progressively collapsed during the sequence: the Amatrice sector during the August 24th 2016, Mw 6.0 event, the Norcia-Visso sector during the October 26th 2016, Mw 5.9 and the 2016 October 30th Mw 6.5 event, and the Campotosto Lake sector during the four January 18th 2017, M〉5 events. The progressive involvement of these three rock volumes, during the seismic sequence is here explained by the occurrence of a low angle detachment that limited the maximum potential depth of the mainshocks and consequently the dimensions of involved rock volumes, therefore limiting the magnitudes of the mainshocks.
    Description: Published
    Description: 101676
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Normal fault earthquake ; fault propagation fold ; Coseismic crustal deformation of the Amatrice-Norcia 2016 sequence
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Ultra-thin clay layers facilitate seismic slip in carbonate faults (2018)
    Details
    Publication Date: 2018-03-23
    Description: Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms-1) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes. This evidence is crucial for hazard assessment along oceanic subduction zones, where pelagic clays participate in seismic slip propagation. Conversely, the reason why, in continental domains, co-seismic slip along faults can propagate up to the Earth's surface is still poorly understood. We document the occurrence of micrometer-thick phyllosilicate-bearing layers along a carbonate-hosted seismogenic extensional fault in the central Apennines, Italy. Using friction experiments, we demonstrate that, at seismic slip rates (1 ms-1), similar calcite gouges with pre-existing phyllosilicate-bearing (clay content ≤3 wt.%) micro-layers weaken faster than calcite gouges or mixed calcite-phyllosilicate gouges. We thus propose that, within calcite gouge, ultra-low clay content (≤3 wt.%) localized along micrometer-thick layers can facilitate seismic slip propagation during earthquakes in continental domains, possibly enhancing surface displacement.
    Description: Published
    Description: 664
    Description: 7T. Struttura della Terra e geodinamica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Crustal-scale fluid circulation and co-seismic shallow comb-veining along the longest normal fault of the central Apennines, Italy (2018)
    Details
    Publication Date: 2019-03-26
    Description: The extensional Val Roveto Fault, which is the longest exhumed potentially-seismogenic structure of central Apennines, Italy, is examined to constrain earthquake-related fluid circulation and fluid sources within shallow carbonate-hosted faults. The study focuses on fault-related comb and slip-parallel veins that are calcite-filled and cut through the principal surface of the Val Roveto Fault. We observe multiple crack-and-seal events characterized by several veining episodes, probably related to different slip increments along the fault plane. We show that vein calcite precipitated in Late Pleistocene time below the present-day outcrop level at a maximum depth of ∼350 m and temperatures between 32 and 64◦C from meteoric-derived fluids modified by reactions with crustal rocks and with a mantle contribution (up to ∼39%). The observed warm temperatures are not compatible with a shallow (≤∼350m) precipitation depth, which, in this region, is dominated by circulation of cold meteoric water and/or shallow groundwater. Based on structural–geochemical data, we propose that deep-seated crust–mantle-derived warm fluids were squeezed upward during earthquakes and were hence responsible for calcite precipitation at shallow depths in co-seismic comb and slip-parallel fractures. As comb-and slip-parallel veins are rather common, particularly along seismogenic extensional faults, we suggest that further studies are necessary to test whether these veins are often of co-seismic origin. If so, they may become a unique and irreplaceable tool to unravel the seismic history of hazardous active faults.
    Description: Published
    Description: 152–168
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Brittle-ductile transition depth versus convergence rate in shallow crustal thrust faults: Considerations on seismogenic volume and impact on seismicity (2018)
    Details
    Publication Date: 2019-03-26
    Description: Earthquakes occur in the Earth’s crust where rocks are brittle, with magnitude increasing with the volume involved in the coseismic stage. Largest volumes are expected in convergent tectonic settings since thrust fault may be even more than 25 times larger than hypocenter depth. In general, the maximum depth of hypocenters within the crust corresponds to the brittle-ductile transition (BDT). The deepening of the BDT increases the potential seismic volume, hence raising the energy released during an earthquake. Here, by means of 2-D thermo-mechanical modelling dedicated to intraplate thrusts and thrusts within fold-and-thrust belts (shallow crust), the deepening of the BDT depth in convergent settings with variable convergence rates is investigated. Results of models characterized by shallow faults (15 ° –20 ° dip) show that BDT depth deepens by 15 km in- creasing the convergence rate from 1 to 10 cm/yr. Steeper thrust faults (25 ° –40 ° dip) show a lower degree of deepening of the BDT ( 5 km) as convergence rate is increased. Calculated BDT depths allow the calculation of maximum seismic volumes involved during thrust earthquakes. Deeper BDT depths obtained assuming higher convergence rates imply larger seismic volumes and an increase of 2 orders of magnitude of the stored potential energy, as effectively observed in nature.
    Description: Published
    Description: 72-81
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Thrust fault earthquakes ; Continental crust ; Seismic volume ; Brittle-ductile transition depth ; Convergence rate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Microstructural evidence for seismic and aseismic slips along clay-bearing, carbonate faults (2018)
    Details
    Publication Date: 2018-03-05
    Description: In this multimethodological study, microstructural observations of fault rocks are combined with micromechanical property analyses (contact resonance atomic force microscopy (CR-AFM)) and with rotary friction experiments (Slow- to High-Velocity rotary-shear friction Apparatus apparatus) to find evidence of seismic to aseismic slip and understand the nanoscale rheology of clay-bearing, carbonate-hosted faults. Fluidized structures, truncated clasts, pores and vesicles, and phyllosilicate nanosized spherules and tubes suggest fast deformation events occurred during seismic slip, whereas clay-assisted pressure-solution processes, clumped clasts, foliation surfaces, and mantled clasts indicate slow deformation events occurred during postseismic/interseismic periods. CR-AFM measurements show that the occurrence of ~5 wt % of clay within the carbonate-hosted gouges can significantly reduce the fault core stiffness at nanoscale. In addition, during high-velocity friction experiments simulating seismic slip conditions, the presence of ultrathin phyllosilicate-bearing (≤3 wt %) layers within calcite gouges, as those observed in the natural fault, show faster dynamic weakening than that of pure calcite gouges. The weak behavior of such layers could facilitate the upward propagation of seismic slip during earthquakes, thus possibly enhancing surface faulting. Microstructural observations and experimental evidence fit some well-known geophysical and geodetic observations on the short- to long-term mechanical behavior of faults such as postseismic/interseismic aseismic creep, interseismic fault locking, and seismic slip propagation up to the Earth's surface. ©2017. American Geophysical Union. All Rights Reserved.
    Description: Published
    Description: 3895 – 3915
    Description: 4T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: 2IT. Laboratori sperimentali e analitici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
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    Volume unbalance on the 2016 Amatrice - Norcia (Central Italy) seismic sequence and insights on normal fault earthquake mechanism (2019)
    Details
    Publication Date: 2019-03-13
    Description: We analyse the Mw 6.5, 2016 Amatrice-Norcia (Central Italy) seismic sequence by means of InSAR, GPS, seismological and geologic data. The 〉1000 km2 area affected by deformation is involving a volume of about 6000 km3 and the relocated seismicity is widely distributed in the hangingwall of the master fault system and the conjugate antithetic faults. Noteworthy, the coseismically subsided hangingwall volume is about 0.12 km3, whereas the uplifted adjacent volumes uplifted only 0.016 km3. Therefore, the subsided volume was about 7.5 times larger than the uplifted one. The coseismic motion requires equivalent volume at depth absorbing the hangingwall downward movement. This unbalance regularly occurs in normal fault-related earthquakes and can be inferred as a significant contribution to coseismic strain accommodated by a stress-drop driven collapse of precursory dilatancy. The vertical coseismic displacement is in fact larger than the horizontal component, consistent with the vertical orientation of the maximum lithostatic stress tensor.
    Description: Published
    Description: id 4250
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Normal fault earthquakes ; Graviquakes ; Volume unbalance ; InSAR data ; Dilated crustal wedge ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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