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  • 1
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    New Insights into Long-Term Aseismic Deformation and Regional Strain Rates from GNSS Data Inversion: The Case of the Pollino and Castrovillari Faults (2021)
    MDPI
    Details
    Publication Date: 2021-01-07
    Description: We present a novel inverse method for discriminating regional deformation and long-term fault creep by inversion of GNSS velocities observed at the spatial scale of intraplate faults by exploiting the different spatial signatures of these two mechanisms. In doing so our method provides a refined estimate of the upper bound of the strain accumulation process. As case study, we apply this method to a six year GNSS campaign (2003–2008) set up in the southern portion of the Pollino Range over the Castrovillari and Pollino faults. We show that regional deformation alone cannot explain the observed deformation pattern and implies high geodetic strain rate, with a WSW-ENE extension of 86±41×10−9/yr. Allowing for the possibility of fault creep, the modelling of GNSS velocities is consistent with their uncertainties and they are mainly explained by a shallow creep over the Pollino fault, with a normal/strike-slip mechanism up to 5 mm/yr. The regional strain rate decrease by about 70 percent and is characterized by WNW-ESE extension of 24±28×10−9/yr. The large uncertainties affecting our estimate of regional strain rate do not allow infering whether the tectonic regime of the area is extensional or strike-slip, although the latter is slightly more likely
    Description: Published
    Description: 2921
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: regional deformation ; fault creep ; GNSS velocities ; inverse theory ; 04. Solid Earth ; 04.03. Geodesy ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Magmatism Along Lateral Slab Edges: Insights From the Diamante‐Enotrio‐Ovidio Volcanic‐Intrusive Complex (Southern Tyrrhenian Sea) (2019)
    Details
    Publication Date: 2021-02-03
    Description: Volcanic-Intrusive complexes often formed along lateral slab-edges as a consequence of subduction-induced mantle flow. We investigate this process in the southern Tyrrhenian Sea by integrating multibeam bathymetry, seismic-reflection data, regional magnetic anomalies data, and seismological data. The interpretation of the data highlights the presence of magmatic intrusions that locally reach the seafloor forming volcanic edifices. Chimneys, lava flows, and laccoliths are observed beneath and surrounding the volcanoes. The emplacement and cooling of the magma occurred during the Brunhes Chron. The volcanoes are not active even if the hydrothermal activity occurs. The volcanic-intrusive complex can be subdivided in a western domain (Diamante and Enotrio seamounts) where strike-slip transpressional faults deform the volcanic edifices, and an eastern domain (Ovidio volcanic seamounts) characterized by flat-topped volcanic edifices. The flat-topped morphology is the result of the interplay between volcanism, erosion, sedimentation and sea-level change. The Ovidio volcanic seamounts formed in an area that experienced at least 60 m of subsidence. Magnetic signatures over the northern side of the Ovidio and Diamante seamounts highlight the presence of a deep-rooted, magnetized feeding system remnant. Volcanic edifices extend above a magma feeding system, characterized by low Vp/Vs ratios. The Diamante-Enotrio-Ovidio volcanic-intrusive complex formed as a consequence of the ascent of subduction-induced mantle flow originated in the northern-western edge of the retreating Ionian slab. We speculate that the magma ascent was controlled by a strike-slip deformation belt, which accommodated the bulk of the shear strain resulting from the formation of a roughly E-W trending, Subduction-Transform Edges Propagator fault.
    Description: Published
    Description: 2581–2605
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: Calabrian Arc, Tyrrhenian Sea, Subduction-induced mantle flow, STEP fault, slab tearing, flat-topped seamount
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    An Intense Earthquake Swarm in the Southernmost Apennines: Fault Architecture from High-Resolution Hypocenters and Focal Mechanisms (2021)
    SSA
    Details
    Publication Date: 2021-06-15
    Description: Between 2010 and 2013, the Pollino Mountains region (south Italy), already proposed as a seismic gap, was affected by a seismic crisis of more than 5000 small-to-moderate earthquakes (maximum magnitude ML 5.0). Preliminary analyses performed in a previous work highlighted that this activity can be ascribed to normal faulting on north-northwest-trending west-dipping dislocation surfaces consistent with the general seismotectonic frame of the southern Apennines. This work contributes additional data and a more sophisticated analyses that highlight new features of the seismic swarm and support a new interpretation for the study area. We obtained high-precision locations and focal mechanisms using the double-difference method and the cut-and-paste waveform inversion method, respectively. The 3D patterns of hypocenters and focal mechanisms consistently image an ∼10-km-long north-northwest-striking and west-dipping fault zone between 5 and 10 km depth, with predominantly extensional kinematics. The high-resolution data show that this zone broadens from north to south as a result of secondary faulting. The depicted geometry, with preliminary geological observation, leads to the hypothesis of multiple seismogenic normal faults rooted into more regional shallow-dipping detachments inherited from the pre-existing Apennine thrust tectonics.
    Description: Published
    Description: 3121–3128
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    How lithospheric subduction changes along the Calabrian Arc in southern Italy: geophysical evidences (2019)
    Details
    Publication Date: 2020-10-27
    Description: Recent tomographic investigations performed down to ~300 km depth in the Calabrian Arc region gave insight in favor of the hypothesis that the Ionian subducting slab is continuous in depth beneath the central part of the Arc, while detachment of the deep portion of the subducting structure may have already taken place beneath the edges of the Arc itself. In the present study, we perform new geophysical analyses to further explore the structure of the subduction system and the structure and kinematics of the crustal units in the study area for a more comprehensive view of the local geodynamic scenario. Local earthquake tomography that we address to the exploration of the upper 40 km in the whole region of southern Italy furnishes P-wave velocity domains, suggesting southeast-ward long-term drifting of the southern Tyrrhenian unit with an advancement front matching well with the segment of Calabrian Arc where the subducting slab was found continuous and trench retreat can be presumed to have been active in the most recent times. This scenario of retreating subduction trench inducing drifting of the lithospheric unit overriding the subducting slab is further supported by the analysis of gravity anomalies, allowing us to better constrain the transitional zones between different subduction modes (continuous vs. detached slab) along the Arc. Also, the relocation of recent crustal seismicity, associated with geostructural data taken from the literature, provides evidence for NW-trending seismogenic structures in northeastern Sicily and northern Calabria that we interpret as Subduction-Transform Edge Propagator (STEP) faults guiding the southeast-ward drifting process of the southern Tyrrhenian unit. Crustal earthquake relocations show also seismolineaments in southern Calabria corresponding to the NE-trending longitudinal structures of the Arc where the great shallow earthquakes of 28 December 1908, and 5 and 7 February 1783 occurred. Seismicity and the extensional stress regime detected in these structures find also reasonable location in the proposed scenario, being interpretable in terms of shallow response of the central segment of the Arc to slab rollback and trench retreat.
    Description: Published
    Description: 1949–1969
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Gravity anomalies and earth structure ; Seismicity and tectonics ; Seismic tomography ; subduction zone processes ; Europe
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Present-day kinematics and deformation processes in the southern Tyrrhenian region: new insights on the northern Sicily extensional belt (2018)
    Details
    Publication Date: 2021-01-07
    Description: We performed a new analysis of updated and accurate sets of seismic and GNSS data relative to the southern Tyrrhenian region. Detailed velocity field and crustal strain distribution coming from integration of episodic and continuous measurements at more than 160 geodetic sites (spanning the 1994-2015 period) have been evaluated together with the spatial distribution of recent seismicity and an updated catalogue of waveform inversion fault-plane solutions relative to the period 1976-2014. In agreement with previous investigations, we have found that the kinematics of the study area is quite homogeneous except for the north-eastern corner of Sicily which moves almost coherently with southern Calabria in response to the SE-ward rollback of the Ionian slab. The rest of the study region shows a NNW-trending velocity field in agreement with the direction of the Nubia-Eurasia convergence and it is mainly interested by a major compressive domain. NNW-oriented compression is particularly highlighted by seismic data along the E-W trending seismic belt located in the southern Tyrrhenian Sea. In the framework of such compressive regime, the E-W trending extensional domain of northern Sicily is also clearly depicted both by seismic and geodetic data. The cause of this extensional domain framed inside a mainly compressive one represents an open question in the recent scientific debate. Comparisons between our results and literature information on regional geology and crustal structure led us to investigate whether the extension could occur as local response to the thrusting dynamics of the southern Tyrrhenian belt, favoured by the presence of pre-existing weakness zones. We then propose a first attempt to evaluate such a possible causal relationship by means of Finite Element Method (FEM) and Coulomb Stress Change (CSC) modelling. In particular, we adopted a FEM approach to investigate the deformation pattern produced by thrust faulting of southern Tyrrhenian belt, along a 2D profile crossing both the compressive belt and the extensional one in northern Sicily. We also estimated the CSC due to the thrust faulting on normal receiving faults fairly reproducing pre-existing structures of northern Sicily. Modelling results indicate that the thrust faulting activity along the Southern Tyrrhenian compressive margin could be effective in promoting extensional processes in northern Sicily. We have so shown that the local response to thrust faulting activity may concur, even in combination with other processes, to generate the crustal stretching of northern Sicily.
    Description: Published
    Description: 418-433
    Description: 1T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Investigating the Pollino mts. seismic sequence south Italy) by high-resolution analysis (2015)
    Details
    Publication Date: 2015-06-13
    Description: We present an high-quality analysis of the space-time evolution of the seismic activity occurred between 2010 and 2013 in the Pollino Mts. region, in the junction area between the Calabrian Arc and the southern Apennines domains (south Italy).
    Description: Published
    Description: Istambul
    Description: 2T. Tettonica attiva
    Description: open
    Keywords: earthquake location ; focal mechanism ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 7
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    A reappraisal of the 1978 Ferruzzano earthquake (southern Italy) from new estimates of hypocenter location and moment tensor inversion (2020)
    Details
    Publication Date: 2020-03-11
    Description: The March 11th, 1978 Ferruzzano earthquake is the most recent moderate-to-major earthquake occurred in the southern Calabrian region (southern Italy), one among the highest seismic risk areas of the whole Mediterranean. Previous information available from the literature on the 1978 earthquake is quite contrasting and not well framed in the regional seismotectonic scenario. In the present study we selected and digitized analog seismograms coming from stations of the Euro-Mediterranean region to invert for the deviatoric seismic moment tensor through a time-domain algorithm properly implemented to analyze data recorded before the advent of the digital era. Moreover, we estimated a new hypocentral location by using original bulletin data and a non-linear probabilistic earthquake location technique working with 3D velocity models. The quality and stability of the obtained results, both for hypocenter location and moment tensor inversion, were accurately checked by several inversion tests. Our results indicate that the 1978 earthquake (i) occurred westward and at a shallower depth respect to previous hypocenter locations, (ii) is characterized by a ca. N-S trending normal faulting mechanism and (iii) has a moment magnitude of 4.7, thus suggesting an overestimate of previous evaluations. This study furnishes new information on the 1978 Ferruzzano earthquake allowing to better frame it in the regional seismotectonic scenario and also proves that the time-domain waveform inversion algorithm applied to digitized old seismograms is capable to successfully invert also M w 〈 5 earthquakes. The obtained results pave the way for future analyses of the early instrumental seismicity potentially capable to furnish new constraints to local and regional seismotectonic modeling.
    Description: Published
    Description: 34-44
    Description: 3T. Sorgente sismica
    Description: 4T. Sismicità dell'Italia
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: Moment tensor inversion ; Waveform analysis ; Analog seismograms ; Non-linear hypocenter location ; Calabrian Arc region ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    New insights on the active degassing system of the Lipari-Vulcano complex (South Italy) inferred from Local Earthquake Tomography (2023)
    Nature PG
    Details
    Publication Date: 2023-01-19
    Description: Seismic tomography is a very powerful and effective approach to look at depths beneath volcanic systems thus helping to better understand their behaviour. The P-wave and S-wave velocity ratio, in particular, is a key parameter useful to discriminate the presence of gas, fluids and melts. We computed the first 3-D overall model of Vp, Vs and Vp/Vs for the Lipari-Vulcano complex, central sector of the Aeolian volcanic archipelago (southern Italy). The investigated area has been characterized in recent times by fumaroles, hydrothermal activity and active degassing. In particular, in the Vulcano Island, several episodes of anomalous increases of fumarole temperature and strong degassing have been recorded in the past decades and the last "crisis", started in September 2021, is still ongoing. For tomographic inversion we collected ~ 4400 crustal earthquakes that occurred in the last thirty years and we used the LOcal TOmography Software LOTOS. The results clearly depicted two low Vp and Vp/Vs anomalies located up to ~ 8 km depths below Vulcano and the western offshore of Lipari, respectively. These anomalies can be associated to the large presence of gas and they furnish a first picture of the gas-filled volumes feeding the main degassing activity of the area.
    Description: Published
    Description: 18867
    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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    The intra-orogenic normal Lakes Fault (Sila, Calabria, southern Italy): new insights from geodetic and seismological data (2024)
    SGI
    Details
    Publication Date: 2024-05-27
    Description: The Calabrian Orogenic Arc (COA) is affected by active extensional and strike-slip tectonics as documented by the presence of N-S and NE-SW trending intra-montane basins bordered by faults, whose slip has caused many destructive earthquakes during the last millennium. By focusing on the central sector of the COA (Sila Massif) through the analysis of new seismological and geodetic datasets, we observed some relevant differences (e.g., seismic activity and hypocentral depths, faulting style, geodetic strain, vertical rates) between its western and eastern sector. The transition between the two sectors occurs in the area of the Lakes Fault, a NW-SE striking and west-dipping fault indicated as the causative source of the 8 June 1638 M 6.8 earthquake. By modelling the available geodetic data, we inferred a dislocation plane whose geometry and kinematics (a prevalent dip-slip component coupled with minor left-lateral strike-slip) is compatible with the real fault reported in literature. This fault only accounts for a small amount of the deformation across northern COA and divides the seismically more active western sector from its eastern counterpart with appreciable geodetic strain and moderate seismicity. Results are encouraging and a similar approach can help in other regions where surface evidence of active faults are rare or non-existing and field geological investigations are hence difficult.
    Description: Published
    Description: 384-397
    Description: OST3 Vicino alla faglia
    Description: JCR Journal
    Keywords: Orogenic arc ; Lakes Fault ; geodesy ; seismology ; analytical model
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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