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  • 1
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    3-D GPR data analysis for high-resolution imaging of shallow subsurface faults: the Mt Vettore case study (Central Apennines, Italy) (2014)
    Oxford University Press
    Details
    Publication Date: 2014-06-21
    Description: The activation of Late Quaternary faults in the Central Apennines (Italy) could generate earthquakes with magnitude of about 6.5, and the Monte Vettore fault system probably belongs to the same category of seismogenetic faults. Such structure has been defined ‘silent’, because of its geological and geomorphological evidences of past activation, but the absence of historical records in the seismic catalogues to be associated with its activation. The ‘Piano di Castelluccio’ intramountain basin, resulting from the Quaternary activity of normal faults, is characterized by a secondary fault strand highlighted by a NW–SE fault scarp: it has been already studied through palaeoseismological trenches, which highlighted evidences of Quaternary shallow faulting due to strong earthquakes, and through a 2-D ground penetrating radar (GPR) survey, showing the first geophysical signature of faulting for this site. Within the same place, a 3-D GPR volume over a 20 20 m area has been collected. The collection of radar echoes in three dimensions allows to map both the vertical and lateral continuity of shallow geometries of the fault zone (Fz), imaging features with high resolution, ranging from few metres to centimetres and therefore imaging also local variations at the microscale. Several geophysical markers of faulting, already highlighted on this site, have been taken as reference to plan the 3-D survey. In this paper, we provide the first 3-D subsurface imaging of an active shallow fault belonging to the Umbria-Marche Apennine highlighting the subsurface fault geometry and the stratigraphic sequence up to a depth of about 5 m. From our data, geophysical faulting signatures are clearly visible in three dimensions: diffraction hyperbolas, truncations of layers, local attenuated zones and varying dip of the layers have been detected within the Fz. The interpretation of the 3-D data set provided qualitative and quantitative geological information in addition to the fault location, like its geometry, boundaries and an estimation of the fault throw.
    Keywords: Marine Geosciences and Applied Geophysics
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 2
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    Integrating multidisciplinary, multiscale geological and geophysical data to image the Castrovillari fault (Northern Calabria, Italy) (2015)
    Oxford University Press
    Details
    Publication Date: 2015-10-30
    Description: The Castrovillari scarps (Cfs) are located in northern Calabria (Italy) and consist of three main WSW-dipping fault scarps resulting from multiple rupture events. At the surface, these scarps are defined by multiple breaks in slope. Despite its near-surface complexity, the faults likely merge to form a single normal fault at about 200 m depth, which we refer to as the Castrovillari fault. We present the results of a multidisciplinary and multiscale study at a selected site of the Cfs with the aim to (i) characterize the geometry at the surface and at depth and (ii) obtain constraints on the fault slip history. We investigate the site by merging data from quantitative geomorphological analyses, electrical resistivity and ground penetrating radar surveys, and palaeoseismological trenching along a ~40 m high scarp. The closely spaced investigations allow us to reconstruct the shallow stratigraphy, define the fault locations, and measure the faulted stratigraphic offsets down to 20 m depth. Despite the varying resolutions, each of the adopted approaches suggests the presence of sub-parallel fault planes below the scarps at approximately the same location. The merged datasets permit the evaluation of the fault array (along strike for 220 m within a 370-m-wide zone). The main fault zone consists of two closely spaced NW–SE striking fault planes in the upper portion of the scarp slope and another fault at the scarp foot. The 3-D image of the fault surfaces shows west to southwest dipping planes with values between 70° and 80°; the two closely spaced planes join at about 200 m below the surface. The 8-to-12-m-high upper fault, which shows the higher vertical displacements, accommodated most of the deformation during the Holocene. Results from the trenching analysis indicate a minimum slip per event of 0.6 m and a maximum short-term slip rate of 0.6 mm yr –1 for the Cf. The shallow subsurface imaging techniques are particularly helpful in evaluating the possible field uncertainties related to postfaulting modification by erosional/depositional/human processes, such as within stream valleys and urbanized zones.
    Keywords: Geodynamics and Tectonics
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 3
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    Rheological behaviour of the crust in Southern Apennine (Italy): results from a thermal and seismological study (2007)
    Blackwell
    Details
    Publication Date: 2022-06-10
    Description: In order to add information on the brittle/ductile transition of the Southern Apennine we investigated a rheological profile of the crust along a WSW-ENE oriented cross-section running from Neapolitan Volcanic Zone to Apulia foreland. The rheological model was obtained computing a thermal modelling and constrained by a re-localization of earthquakes of the area. Results show that the area is characterized by horizontal rheological variations, with two horizons interlayered with ductile horizons, that are quite predominant with respect to vertical ones. The horizontal stratification of lithospheric rheology has important geodynamic consequence and could provide new insights to better understand the tectonic processes which have played a major role to construct the Southern Apennine belt. Results of this study suggested that well constrained rheological models, built integrating information from both re-located earthquakes and thermal state, could give important hints on the mechanical behaviour of the crust and its related tectonic processes.
    Description: Published
    Description: 353-359
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: rheology ; crust ; Apennine ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Gravity and Magnetic Modeling of Central Italy: Insights Into the Depth Extent of the Seismogenic Layer (2019)
    Details
    Publication Date: 2022-06-10
    Description: The recent 2016–2017 seismic sequence in Central Italy has prompted the investigation of several geological and geophysical data in order to derive more accurate subsurface geological models. We present the results of combined gravity and magnetic modeling performed along three sections crossing the area of the seismic sequence in order to evaluate the geological parameters controlling or affecting the thickness of the seismogenic layer of this part of the Apennines. The models are constructed using all the available geological and petrophysical constraints derived from previous studies. Resulting models are consistent with the top of the basement located at 8‐ to 12‐km depth and contribute to the geological and geophysical understanding of the area investigating the role of the basement in the seismic events. The basement, involved in Miocene thrusting, formed the base of seismicity for the recent seismic sequence in the area. Moreover, the models provide information about the nature and composition of the basement and lower crust. Finally, these findings contribute in the investigation of the mechanisms controlling the thickness of the seismogenic layer in extensional postorogenic scenarios.
    Description: Published
    Description: 2157-2172
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    The role of rheology, crustal structures and lithology in the seismicity distribution of the northern Apennines (2018)
    Details
    Publication Date: 2022-06-10
    Description: The Northern Apennines of Italy is a unique area to study active crustal processes due to the availability of high-resolution subsurface geology (deep borehole and seismic profiles) and seismicity (back-ground and seismic sequences) data. In this work we have investigated the relationship between crustal structures and lithologies, rheological profiles and seismicity cut-off by constructing three integrated profiles across the Umbria-Marche Apennines. At first approximation we observe a good correspondence between the background seismicity cut-off and the modelled brittle ductile transition (BDT): 90% of the seismic activity is located above the transition. In the area characterized by active extension, where the majority of the seismicity is occurring, most of the crustal earthquakes are confined within the brittle layer at depth 〈 12 km. In areas where the brittle layer is affected by regional structures, we observe an active role played by these structures in driving the seismicity distribution. One example is the region where the gently eastward dipping Altotiberina low-angle normal fault is present, where the seismicity cut-off is completely controlled by this detachment that separates an active hanging-wall from an almost aseismic foot-wall block. At smaller scale also the lithology plays a strong control on the seismicity distribution. We observe that the largest earthquakes of the area, 5.5 〈 M 〈 6.0, do not nucleate at the base of the BDT but they occur at the base of the sedimentary cover. Our work suggests that rheology and therefore the position of the brittle ductile transition exerts a role at regional scale for the occurrence of crustal seismicity, however crustal structures and lithology play the major role at a more local scale and therefore they need to be considered for a better understanding of earthquake distribution within the seismogenic layer.
    Description: Published
    Description: 280-291
    Description: 1T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: crustal structure ; solid earth
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Integrating multidisciplinary, multiscale geological and geophysical data to image the Castrovillari fault (Northern Calabria, Italy) (2019)
    Details
    Publication Date: 2022-06-10
    Description: This article has been accepted for publication in Geophysical Journal International ©: The Authors 2015. 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: The Castrovillari scarps (Cfs) are located in northern Calabria (Italy) and consist of three main WSW-dipping fault scarps resulting from multiple rupture events. At the surface, these scarps are defined by multiple breaks in slope. Despite its near-surface complexity, the faults likely merge to form a single normal fault at about 200 m depth, which we refer to as the Castrovillari fault. We present the results of a multidisciplinary and multiscale study at a selected site of the Cfs with the aim to (i) characterize the geometry at the surface and at depth and (ii) obtain constraints on the fault slip history. We investigate the site by merging data from quantitative geomorphological analyses, electrical resistivity and ground penetrating radar surveys, and palaeoseismological trenching along a ∼40 m high scarp. The closely spaced investigations allow us to reconstruct the shallow stratigraphy, define the fault locations, and measure the faulted stratigraphic offsets down to 20 m depth. Despite the varying resolutions, each of the adopted approaches suggests the presence of sub-parallel fault planes below the scarps at approximately the same location. The merged datasets permit the evaluation of the fault array (along strike for 220 m within a 370-m-wide zone). The main fault zone consists of two closely spaced NW–SE striking fault planes in the upper portion of the scarp slope and another fault at the scarp foot. The 3-D image of the fault surfaces shows west to southwest dipping planes with values between 70◦ and 80◦; the two closely spaced planes join at about 200 m below the surface. The 8-to-12-m-high upper fault, which shows the higher vertical displacements, accommodated most of the deformation during the Holocene. Results from the trenching analysis indicate a minimum slip per event of 0.6 m and a maximum short-term slip rate of 0.6 mm yr–1 for the Cf. The shallow subsurface imaging techniques are particularly helpful in evaluating the possible field uncertainties related to postfaulting modification by erosional/depositional/human processes, such as within stream valleys and urbanized zones.
    Description: This study has benefited from funding provided by the Italian Presidenza del Consiglio dei Ministri - Dipartimento della Protezione Civile (DPC).
    Description: Published
    Description: 1847–1863
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: Image processing ; Tomography ; Geomorphology ; Palaeoseismology ; Fractures and faults ; 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Experimental constraints on the rheology, eruption, and emplacement dynamics of analog lavas comparable to Mercury's northern volcanic plains Authors (2018)
    Details
    Publication Date: 2022-06-10
    Description: We present new viscosity measurements of a synthetic silicate system considered an analogue for the lava erupted on the surface of Mercury. In particular, we focus on the northern volcanic plains (NVP), which correspond to the largest lava flows on Mercury and possibly in the Solar System. High-temperature viscosity measurements were performed at both superliquidus (up to 1736 K) and subliquidus conditions (1569–1502 K) to constrain the viscosity variations as a function of crystallinity (from 0 to 28%) and shear rate (from 0.1 to 5 s 1). Melt viscosity shows moderate variations (4–16 Pa s) in the temperature range of 1736–1600 K. Experiments performed below the liquidus temperature show an increase in viscosity as shear rate decreases from 5 to 0.1 s 1, resulting in a shear thinning behavior, with a decrease in viscosity of ~1 log unit. The low viscosity of the studied composition may explain the ability of NVP lavas to cover long distances, on the order of hundreds of kilometers in a turbulent flow regime. Using our experimental data we estimate that lava flows with thickness of 1, 5, and 10 m are likely to have velocities of 4.8, 6.5, and 7.2 m/s, respectively, on a 5° ground slope. Numerical modeling incorporating both the heat loss of the lavas and its possible crystallization during emplacement allows us to infer that high effusion rates (〉10,000 m3/s) are necessary to cover the large distances indicated by satellite data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft.
    Description: Published
    Description: 1522–1538
    Description: 1V. Storia eruttiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    The gravity anomaly of Mount Amiata; different approaches for understanding anomaly source distribution (2018)
    Details
    Publication Date: 2022-06-10
    Description: This article has been accepted for publication in Geophysical Journal Internationa ©: The Authors 2017. 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: In this work, the gravity anomaly signal beneath Mount Amiata and its surroundings have been analysed to reconstruct the subsurface setting. In particular, the work focuses on the investigation of the geological bodies responsible for the Bouguer gravity minimum observed in this area. Different approaches for understanding the Bouguer gravity anomaly source distribution, including the calculation of the first vertical derivative of the gravity signal, the estimation of the depth source using power spectrum analysis and the pseudo-3-D forward modeling, have been considered. The gravity data employed were acquired from different institutions ENI, OGS, USDMA and Servizio Geologico d'Italia and collected in a unique data set kindly made available by ENI. It comes from about 50 000 stations, randomly distributed, which cover Central Italy, with a spacing of less than 1 km. We dedicated an active effort in: Defining the stratigraphic model (i.e. definition of the primary lithomechanical layers within the sedimentary cover and the upper crust). Calculation of a new data set of density data derived from the velocity data collected by active seismic surveys. Integration of stratigraphy, literature and new data in a comprehensive model. The results of this study depict a body, with a density of 2.35 g cm−3, representing the remnant magmatic chamber of Mount Amiata, which is responsible of the observed gravimetric minimum. The top of the magmatic body is upward-convex, dislocated at a depth comprised between 4.5 (beneath the volcano) and 7.5 km (in the peripheral zones) and draped by 2 km thick, highly fractured hard rocks that could represent the fractured aureole of the magmatic body itself. The 3-D modeling also defines the geometry of the Neogene Radicofani basin, close to the eastern flank of the Mount Amiata and is imaged as a bowl-shaped basin with an average depth of about 1500 m, and a maximum depth of about 2000 m reached towards north.
    Description: Published
    Description: 865–882
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Seismic Reflection Profiles and Subsurface Geology of the Area Interested by the 2016-2017 Earthquake Sequence (Central Italy) (2019)
    Details
    Publication Date: 2022-06-10
    Description: Starting from 24 August 2016, a long seismic sequence, including nine Mw 〉 5.0 earthquakes, struck a wide area of the Central Italy. A large amount of geological, geodetic, and seismological data envisages a complex system of NNW-SSE trending, seismogenic normal faults. These active tectonic structures are well known at the surface and consistent with previous seismotectonic studies. In order to improve the comprehension of the seismotectonic framework of this seismic sequence, we provide a novel reconstruction of the subsurface geology of the area close to the NorciaMw 6.5 mainshock (30 October 2016), based on previously unpublished seismic reflection profiles and available geological data. All the data have been synthesized along a 47 km long, WSW-ENE trending geological cross section, interpreted down to a depth of 12 km. Comparing the subsurface geological model with the available seismological data, we find that the majority of seismicity is confined within the sedimentary sequence and does not penetrate the underlying basement. The basement has been constrained at depths of 8 to 11 km and coincides with the cutoff of the seismicity. We have also traced the trajectories of the seismogenic normal faults activated during this seismic sequence, reconciling the high-angle (dip〉65°) normal faults exposed at the surface, with their angle (dip 〈 50°) at hypocentral depths. The results of this study may be useful for better understanding the rheological properties of the seismogenic rock volume, as well as the coseismic deformations of the topographic surface observed by geodetic techniques and field mapping.
    Description: Published
    Description: 1116-1137
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
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    The geodynamical evolution of the Northern Apennines chain (Central Italy): an exploring numerical model (2004)
    In:  Physics of the Earth and Planetary Interiors
    Details
    Publication Date: 2020-02-12
    Type: info:eu-repo/semantics/article
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