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  • 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics  (38)
  • American Geophysical Union  (25)
  • AGU  (13)
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  • 1
    Publication Date: 2022-06-14
    Description: Rayleigh wave tomography provides images of the shallow mantle shear wave velocity structure beneath the Gulf of California. Low-velocity zones (LVZs) are found on axis between 26 and 50 km depth beneath the Guaymas Basin but mostly off axis under the other rift basins, with the largest feature underlying the Ballenas Transform Fault. We interpret the broadly distributed LVZs as regions of partial melting in a solid mantle matrix. The pathway for melt migration and focusing is more complex than an axis-centered source aligned above a deeper region of mantle melt and likely reflects the magmatic evolution of rift segments. We also consider the existence of solid lower continental crust in the Gulf north of the Guaymas Basin, where the association of the LVZs with asthenospheric upwelling suggests lateral flow assisted by a heat source. These results provide key constraints for numerical models of mantle upwelling and melt focusing in this young oblique rift.
    Description: Published
    Description: 1766–1774
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: Low velocities in the Gulf upper mantle are interpreted as partial melting ; Partial melting under the Guaymas Basin and off axis of the other rift basins ; Lower crustal flow assisted by heat source in N Gulf near mantle upwelling ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-12-16
    Description: We performed 31 friction experiments on glassy basalts (GB) and glass-free basalts (GFB) at slip rates up to 6.5 m s−1 and normal stress up to 40 MPa (seismic conditions). Frictional weakening was associated to bulk frictional melting and lubrication. The weakening distance (Dw) was about 3 times shorter in GB than in GFB, but the steady state friction was systematically higher in GB than in GFB. The shorter Dw in GB may be explained by the thermal softening occurring at the glass transition temperature (Tg ~500°C), which is lower than the bulk melting temperature (Tm ~1250°C) of GFB. Postexperiment microanalyses suggest that the larger crystal fraction measured in GB melts results in the higher steady state friction value compared to the GFB melts. The effect of interstitial glass is to facilitate frictional instability and rupture propagation in GB with respect to GFB.
    Description: Published
    Description: 348-355
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: JCR Journal
    Description: embargoed_20160201
    Keywords: Earthquakes ; Friction ; Basalts ; Interstitial glass ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2021-09-08
    Description: We report new paleomagnetic and anisotropy of magnetic susceptibility (AMS) results from upper Tortonian to middle Pleistocene sediments which were deposited upon and adjacent to active thrust structures in southwestern Sicily. The data show that the Plio-Pleistocene sediments from the Belice and Menfi basins (covering the Saccense shelf limestones) underwent any internal shortening after the early Pleistocene (Santernian), as well as any net rotation. Sediments around this area (which overlie basinal Meso-Cenozoic successions) record systematic rotations: one upper Tortonian site to the west is ~30° counterclockwise rotated, while to the east, lower Pliocene to middle lower Pleistocene sites within the Gela Nappe domain show 25° to 56° clockwise (CW) rotations. These data show that the ductile basinal sediments were bent and rotated around the rigid Saccense carbonates during the thin-skinned southward propagation of the orogenic front. We document here that the coastal sediments from the southwestern Gela Nappe underwent both a post middle early Pleistocene ~30° CW rotation and a post middle Pleistocene E-W to ESE-WNW flattening (revealed by AMS). Our data then constrain to the late Pleistocene-Holocene the age of the last shortening episode occurring in the southwestern Gela Nappe front. Pleistocene rotations of similar amount also characterize the Sicanian domain, implying that it was incorporated in the Gela Nappe wedge during the recentmost episodes of deformation. This evidence allows us to better understand the very large (up to 114°) post Mesozoic rotations reported by Channell et al. [1980, 1990] for the Sicanian limestones, as related to both Miocene (or older?) deformational episodes and the Plio-Pleistocene evolution of the Gela Nappe.
    Description: Published
    Description: 1178-1197
    Description: JCR Journal
    Description: reserved
    Keywords: paleomagnetism ; tectonic rotations ; Sicily ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2021-01-04
    Description: We present a neotectonic model of ongoing lithosphere deformation and a corresponding estimate of long-term shallow seismicity across the Africa-Eurasia plate boundary, including the eastern Atlantic, Mediterranean region, and continental Europe. GPS and stress data are absent or inadequate for the part of the study area covered by water. Thus, we opt for a dynamic model based on the stress-equilibrium equation; this approach allows us to estimate the long-term behavior of the lithosphere (given certain assumptions about its structure and physics) for both land and sea areas. We first update the existing plate model by adding five quasi-rigid plates (the Ionian Sea, Adria, Northern Greece, Central Greece, and Marmara) to constrain the deformation pattern of the study area. We use the most recent datasets to estimate the lithospheric structure. The models are evaluated in comparison with updated datasets of geodetic velocities and the most compressive horizontal principal stress azimuths. We find that the side and basal strengths drive the present-day motion of the Adria and Aegean Sea plates, whereas lithostatic pressure plays a key role in driving Anatolia. These findings provide new insights into the neotectonics of the greater Mediterranean region. Finally, the preferred model is used to estimate long-term shallow seismicity, which we retrospectively test against historical seismicity. As an alternative to reliance on incomplete geologic data or historical seismic catalogs, these neotectonic models help to forecast long-term seismicity, although requiring additional tuning before seismicity rates are used for seismic hazard purposes.
    Description: Published
    Description: 5311–5342
    Description: 1T. Geodinamica e interno della Terra
    Description: 2T. Tettonica attiva
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: open
    Keywords: Tectonics ; Earthquake rates ; 04. Solid Earth::04.02. Exploration geophysics::04.02.03. Heat flow ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.07. Tectonophysics::04.07.01. Continents ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2020-11-26
    Description: The Tindari Fault System (southern Tyrrhenian Sea, Italy) is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab. Onshore structural data, an offshore seismic reflection profile, and earthquake data are analyzed to constrain the present geometry of the Tindari Fault System and its tectonic evolution since Neogene, including the present seismicity. Results show that this zone of deformation consists of a broad NNW trending system of faults including sets of right-lateral, left-lateral, and extensional faults as well as early strike-slip faults reworked under late extension. Earthquakes and other neotectonic data provide evidence that the Tindari Fault System is still active in the central and northern sectors and mostly accommodates extensional or rightlateral transtensional displacements on a diffuse array of faults. From these data, a multiphase tectonic history is inferred, including an early phase as a right-lateral strike-slip fault and a late extensional reworking under the influence of the subductionrelated processes, which have led to the formation of the Tyrrhenian back-arc basin. Within the present, regional, geodynamic context, the Tindari Fault System is interpreted as an ongoing accommodation zone between the adjacent contractional and extensional crustal compartments, these tectonic compartments relating to the complex processes of plate convergence occurring in the region. The Tindari Fault System might also be included in an incipient, oblique-extensional, transfer zone linking the ongoing contractional belts in the Calabrian-Ionian and southern Tyrrhenian compartments.
    Description: Published
    Description: TC2006
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2017-04-04
    Description: The active tectonics at the front of the Southern Apennines and in the Adriatic foreland is characterized by E-W striking, right-lateral seismogenic faults, interpreted as reactivated inherited discontinuities. The best studied among these is the Molise-Gondola shear zone (MGsz). The interaction of these shear zones with the Apennines chain is not yet clear. To address this open question we developed a set of scaled analogue experiments, aimed at analyzing: 1) how dextral strike-slip motion along a pre-existing zone of weakness within the foreland propagates toward the surface and affects the orogenic wedge; 2) the propagation of deformation as a function of displacement; 3) any insights on the active tectonics of Southern Italy. Our results stress the primary role played by these inherited structures when reactivated, and confirm that regional E-W dextral shear zones are a plausible way of explaining the seismotectonic setting of the external areas of the Southern Apennines.
    Description: INGV, Università degli Studi di Pavia
    Description: Published
    Description: 21
    Description: open
    Keywords: Active strike-slip fault ; sandbox model ; southern Italy ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: We modeled Pnl phases from several moderate magnitude earthquakes in the eastern Mediterranean to test methods and develop path calibrations for determining source parameters. The study region, which extends from the eastern part of the Hellenic arc to the eastern Anatolian fault, is dominated by moderate earthquakes that can produce significant damage. Our results are useful for analyzing regional seismicity as well as seismic hazard, because very few broadband seismic stations are available in the selected area. For the whole region we have obtained a single velocity model characterized by a 30 km thick crust, low upper mantle velocities and a very thin lid overlaying a distinct low velocity layer. Our preferred model proved quite reliable for determining focal mechanism and seismic moment across the entire range of selected paths. The source depth is also well constrained, especially for moderate earthquakes.
    Description: Published
    Description: N/A or not JCR
    Description: reserved
    Keywords: Body wave propagation ; earthquake parameters ; lithosphere ; upper-mantle ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2017-04-04
    Description: This study concerns the unstable scarp named Sciara del Fuoco (SDF) at Stromboli volcano, merging geostructural observations, live-cam records in the visible and IR bands, analysis of vertical aerial photographs, and seismic records. These are used to assess morpho-structural changes between 2002 and 2004. The onset of the lava effusion on 28 December, 2002 preceded a gravitational collapse by two days, affecting a wide area of the SDF above and below sea level. We surmise that the collapse enhanced latent instability of the scarp. The 2002–2003 lava flows had a remarkable stabilizing effect on wide portions (〉50%) of the SDF, whilst erosive phenomena continued in the zone not covered by lava. This caused unrelenting regression of the upper landslide scarp toward the summit craters in the form of rockfalls and debris flows. If the crater conduit were involved in the sliding, then a change in eruptive behavior cannot be excluded.
    Description: Published
    Description: L09304
    Description: reserved
    Keywords: NONE ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2017-04-04
    Description: The soil CO2 flux on Mt. Etna as recorded by the ETNAGAS network (an automatic system for measuring soil CO2 flux and meteorological parameters) started to increase strongly about 5 months prior to the onset of the 2004–2005 eruption and decreased a few months before the end of the eruption. Time delays in the occurrences of anomalies in soil CO2 flux at different sites in the geochemical network constrain the relationship between soil CO2 flux distributions and the tectonic framework of Etna volcano. The anomalies observed before the 2004–2005 eruption support the intrusion of new undegassed magma into the upper feeding system of the volcano (〈20 km below sea level). Magma subsequently rose slowly in the volcano conduits, thereby triggering the onset of the 2004–2005 eruption. The time delays in the occurrences of anomalies in combination with spectral analysis indicate the importance of tectonic and volcanotectonic structures in driving the ascent of deep gases within the crust. Moreover, greatest amplitude pulsations of the low-frequency components of the CO2 flux signals were correlated with the paroxystic activities of the 2004–2005 eruption. This study confirms that CO2 flux variation is a useful indicator for volcanic activity in the surveillance of the Mt. Etna and similar basaltic volcanoes.
    Description: Dipartimento Protezione Civile Ministero degli Interni
    Description: Published
    Description: B09206
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 flux ; Continuous monitoring of soil CO2 flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: We discuss the tectonic implications of a new residual magnetic map of the Apennine belt/Adriatic-Apulian foreland obtained by integrating ground and offshore data sets [Chiappini et al., 2000a]. Negative anomalies are documented over the Adriatic-Apulian foreland areas, whereas the external Apennine belt is characterized by a ubiquitous lowamplitude (〈30 nT), long-wavelength positive anomaly. In the central northern Apennines, three 100 km wide more intense (100–200 nT) round-shaped anomalies are superimposed to the long-wavelength feature. Finally, in the Tyrrhenian Sea and margins, high-intensity, short-wavelength positive-negative couplets coincide with magmatic outcrops or bodies at shallow depth. The low-amplitude anomaly pattern over Italy suggests that the magnetic basement beneath the Triassic evaporites is ubiquitously incorporated in the external belt compressive fronts, implying a thick-skinned tectonic style for the external Apennines. The new residual magnetic map resolves the inconsistency between previous aeromagnetic data [AGIP SpA. Italia, 1981], which suggested a lack of basement involvement in the Apennine belt, and recent seismic data, which imaged deep reflectors penetrating the basement. Two magnetic models along NE-SW transects in the northern and southern Apennines suggest consistent structural styles. In the northern Apennines, positive anomalies roughly coincide with the external compressive fronts, although there are local second-order differences between the belt front and the edges of the anomaly. Here the magnetic data show that the basement rises southwestward along the thrust fronts from 6–7 km depth in the Adriatic foreland to 2–3 km depth in the axial belt, where some exploration wells have penetrated basement. Within the belt front, basement exhumation is inferred to occur along high-angle, low-displacement thrust faults inverting preexisting normal faults. In the southern Apennines, a remarkable positive magnetic anomaly is parallel with and tens of kilometers southwest of the belt front. Seismic data and oil wells show that the basement surface cannot be shallower in the belt than in the foreland. Therefore the observed magnetic anomaly is produced by strongly magnetic basement beneath the belt, likely an internal crustal wedge tectonically interposed between the Apulian carbonate sequences and basement.
    Description: Published
    Description: 2290
    Description: JCR Journal
    Description: reserved
    Keywords: Magnetic anomalies ; Potential fields ; Apennines ; Crustal modelling ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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