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  • 04.07. Tectonophysics
  • Statistical investigations
  • 2015-2019  (48)
  • 1995-1999  (161)
  • 1950-1954  (2)
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  • 1
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    The combined inversion of seismological and GOCE gravity data: New insights into the current state of the Pacific lithosphere and upper mantle (2017)
    Elsevier
    Details
    Publication Date: 2021-02-26
    Description: In this study we combine seismological and GOCE satellite gravity information by using a Bayesian-like technique, with the aim of inferring the density structure of the Pacific (90°N 90°S) (121°E 60°W) lithosphere and upper mantle. We recover a 1° × 1° 3-D density model, down to 300 km depth, which explains gravity observations with a variance reduction of 67.41%. The model, with an associated a posteriori standard deviation, provides a significant contribution to understanding the evolution of the Pacific lithosphere and answers to some debated geodynamic questions. Our methodology enables us to combine the recovery of density parameters with the optimum density-vSV scalings. The latter account for both seismological and gravity observations in order to identify the regions characterized by chemically-induced density heterogeneities which add to the thermally-induced anoma- lies. Chemically-modified structures are found west of the East Pacific Rise (EPR) and are of relevant amplitude both below the north-western side of the Pacific Plate, at the base of the lithosphere, and up to 100 km depth beneath the Hawaiian and Super Swell regions, thus explaining the anomalous shallow regions without invoking the thermal buoyancy as the sole justification. Coherently with the chemically modified structures, our results a) support a lighter and more buoyant lithosphere than that predicted by the cooling models and b) are in favor of the hypothesized crustal underplating beneath the Hawaiian chain and be- neath the volcanic units in the southern branch of the Super Swell region. The comparison between calculated mantle gravity residuals and residual topography a) suggests a lateral viscosity growth associated with the increasing thickness and density of the Plate and b) correlates well with sub-lithospheric mantle flow from the EPR towards west, up to the Kermadec and Tonga Trench in the south and the Kuril-Kamchatka Trench in the north.
    Description: Published
    Description: 101-115
    Description: 7T. Struttura della Terra e geodinamica
    Description: JCR Journal
    Keywords: Pacific lithosphere ; GOCE ; Satellite gravity ; Seismological observations ; Residual Topography ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    How much does geometry of seismic sources matter in tsunami modeling? A sensitivity analysis for the Calabrian subduction interface (2018)
    Details
    Publication Date: 2020-10-22
    Description: The geometry of seismogenic sources could be one of the most important factors concurring to control the generation and the propagation of earthquake-generated tsunamis and their effects on the coasts. Since the majority of potentially tsunamigenic earthquakes occur offshore, the corresponding faults are generally poorly constrained and, consequently, their geometry is often oversimplified as a planar fault. The rupture area of mega-thrust earthquakes in subduction zones, where most of the greatest tsunamis have occurred, extends for tens to hundreds of kilometers both down dip and along strike, and generally deviates from the planar geometry. Therefore, the larger the earthquake size is, the weaker the planar fault assumption become. In this work, we present a sensitivity analysis aimed to explore the effects on modeled tsunamis generated by seismic sources with different degrees of geometric complexities. We focused on the Calabrian subduction zone, located in the Mediterranean Sea, which is characterized by the convergence between the African and European plates, with rates of up to 5 mm/yr. This subduction zone has been considered to have generated some past large earthquakes and tsunamis, despite it shows only in-slab significant seismic activity below 40 km depth and no relevant seismicity in the shallower portion of the interface. Our analysis is performed by defining and modeling an exhaustive set of tsunami scenarios located in the Calabrian subduction and using different models of the subduction interface with increasing geometrical complexity, from a planar surface to a highly detailed 3D surface. The latter was obtained from the interpretation of a dense network of seismic reflection profiles coupled with the analysis of the seismicity distribution. The more relevant effects due to the inclusion of 3D complexities in the seismic source geometry are finally highlighted in terms of the resulting tsunami impact.
    Description: Unpublished
    Description: New Orleans
    Description: 1T. Deformazione crostale attiva
    Description: 5T. Modelli di pericolosità sismica e da maremoto
    Keywords: tsunami ; seismic source geometry ; 03.03. Physical ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 3
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    On the increasing size of the orogens moving from the Alps to the Himalayas in the frame of the net rotation of the lithosphere (2018)
    Details
    Publication Date: 2020-12-15
    Description: The tectonic equator represents the great circle of the non-random mainstream of plate motions and it is inclined about 30° relative to the geographic equator. Divergence or convergence rates among plates are in average faster along the tectonic equator and they tend to decrease toward the polar areas. Moving from Western Europe to eastern Asia, the mainstream is roughly oriented southwest northeast. Here we show how this pattern may have played a role in determining the dimension of the Alpine-Himalayas orogenic belt, which is increasing in size and thickness moving from west-northwest to east-southeast, i.e., moving from high-latitude to low-latitude of the tectonic mainstream of plates. The Alps are in average 200–250 km wide, whereas the Himalayas are regularly 〉 1000 km wide. Moreover, due to the “westerly” polarization of the lithospheric mainstream relative to the mantle, either the net-rotation or the westward drift of the lithosphere, the subduction zones can be differentiated into two types, 1) increasing or 2) decreasing the lithospheric thickness. The Alpine-Himalayas system pertains to type 1 and it may represent a prototype of the continental lithosphere growth since the Archean. The increasing size of the orogens moving from the Alps to the Himalayas is presently concentrated in the northern hemisphere of the tectonic mainstream because subduction type 2 dominated the western margin of the Pacific ocean, hence preventing continental growth in the southern hemisphere in that longitude range. Therefore, the largest growth of continental crust and mantle lithosphere should have occurred along the tectonic equator, but only where type 1 subduction was generated.
    Description: Published
    Description: 2-13
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    First seismic evidence for continental subduction beneath the Western Alps (2018)
    Details
    Publication Date: 2021-03-05
    Description: The first discovery of ultrahigh-pressure coesite in the European Alps 30 years ago led to the inference that a positively buoyant continental crust can be subducted to mantle depth; this had been considered impossible since the advent of the plate tectonics concepts. Although continental subduction is now widely accepted, there remains debate because there is little direct (geophysical) evidence of a link between exhumed coesite at the surface and subducted continental crust at depth. Here we provide the first seismic evidence for continental crust at 75 km depth that is clearly connected with the European crust exactly along the transect where coesite was found at the surface. Our data also provide evidence for a thick suture zone with downward-decreasing seismic velocities, demonstrating that the European lower crust underthrusts the Adriatic mantle. These findings, from one of the best-preserved and long-studied ultrahigh-pressure orogens worldwide, shed decisive new light on geodynamic processes along convergent continental margins.
    Description: Published
    Description: 815-818
    Description: 7T. Struttura della Terra e geodinamica
    Description: JCR Journal
    Keywords: 04.01. Earth Interior ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Insights into the fragmentation of the Adria Plate (2018)
    Details
    Publication Date: 2020-11-30
    Description: This study gives an interpretation of the current tectonics and kinematics of the Adria Plate, a region mostly coinciding with Italy and its surroundings. We have examined the spatial distribution and kinematics of seismicity by using an updated dataset obtained integrating the available catalogues of earthquakes and focal mechanisms. Moreover, to highlight the distribution of seismicity and of the asso- ciated strain patterns, we have elaborated a seismic flux map of the Italian region, which is a map of the energy released per unit time and per unit area. Seismic flux represents the energy released and provides a synthetic and continuous view of areas with greater seismicity and associated strain patterns with respect to the plot of earthquakes only. The seismic data, and the results of some elaborations car- ried out using these datasets have been compared with the present-day state of stress and slip rates of the major active faults of some sectors of Italy, as well as with the horizontal kinematics highlighted by GPS observations. The distribution and kinematics of earthquakes and active faults, the seismic flux, and GPS velocities, suggest that the Adria Plate is currently behaving as an ensemble of independent blocks rather than as a unique rigid plate. The Adria Plate can be thus subdivided into three major blocks and a number of smaller blocks moving independently under the action of a first-order mechanism related to the ongoing, roughly N-S, Europe-Africa convergence vector. This complicated setting may promote the occurrence of mutual relationships between blocks, and generate peculiar local kinematics causing seis- mic activity. We infer that the great majority of the seismic events occur at the boundaries of the main or minor blocks, and therefore the alignments of seismicity allows the individuation of the different blocks and the main seismogenic belts. A major crustal structure subdivides the Adria Plate into a western and two eastern blocks, and approximately coincides with the axial zone of the Apennines along which most of the seismicity is concentrated.
    Description: Published
    Description: 121-138
    Description: 1T. Deformazione crostale attiva
    Description: 1IT. Reti di monitoraggio
    Description: 4IT. Banche dati
    Description: JCR Journal
    Keywords: Adria plate ; Apennines ; Active tectonics ; Seismicity ; Seismic flux ; GPS ; 04.06. Seismology ; 04.03. Geodesy ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    The role of continental margins in the final stages of arc formation: Constraints from teleseismic tomography of the Gibraltar and Calabrian Arc (Western Mediterranean) (2019)
    Details
    Publication Date: 2021-03-02
    Description: The deep seismicity and lateral distribution of seismic velocity in the CentralWesternMediterranean, point to the existence under the Alboran and Tyrrhenian Seas of two lithospheric slabs reaching the mantle transition zone. Gibraltar and Calabrian narrow arcs correspond to the slabs. Similarities in the tectonic and mantle structure of the two areas have been explained by a common subduction and roll-back mechanism, in which the two arcs are symmetrical end members. We present a new 3-D tomographic model at mantle scale for the Calabrian Arc and compare it with a recently published model for the Gibraltar Arc by Monna et al. (2013a). The two models, calculated with inversion of teleseismic phase arrivals, have a scale and parametrization that allow for a direct comparison. The inclusion in both inversions of ocean bottom seismometer broadband data improves the resolution of the areas underlying the seafloor networks. This additional information is used to resolve the deep structure and constrain the reconstruction of the Central Western Mediterranean geodynamic evolution. The Gibraltar tomography model suggests that the slab is separated from the Atlantic oceanic domain by a portion of African continental margin, whereas the Calabrian model displays a continuous oceanic slab that is connected, via a narrow passage (~350 km), to the Ionian basin oceanic domain. Starting from the comparison of the two models we propose the following interpretation: within the Mediterranean geodynamic regime (dominated by slab rollback) the geometry of the African continental margin, located on the lower plate, represents a critical control on the evolution of subduction. As buoyant continental lithosphere entered the subduction zones, slab pull caused tears in the subducted lithosphere. This tectonic response,which occurred in the final stages of arc evolution and was strongly controlled by the paleogeography of the subducted plates, explains the observed differences between the Gibraltar and Calabrian Arcs.
    Description: Published
    Description: 135-152
    Description: 7T. Struttura della Terra e geodinamica
    Description: JCR Journal
    Keywords: Teleseismic tomography ; Upper mantle ; Gibraltar Arc ; Calabrian Arc ; Subduction zone ; 04.06. Seismology ; 04.01. Earth Interior ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Geochemical characteristics of soil radon and carbon dioxide within the Dead Sea Fault and Karasu Fault in the Amik Basin (Hatay), Turkey (2017)
    Details
    Publication Date: 2021-06-15
    Description: The study area is close to the boundary of three tectonic plates (Anatolian, Arabian, and African plates) and is characterized by important tectonic lineaments, which consist mainly of the Dead Sea Fault (DSF), the Karasu Fault, and the East Anatolian Fault (EAF) systems. To understand the origin of soil gas emanation and its relationships with the tectonics of the Amik Basin (Hatay), a detailed soil gas sampling was systematically performed. Together with CO2 flux measurements, N220 soil gas samples were analyzed for Rn and CO2 concentrations. The distribution of soil Rn (kBq/m3), CO2 concentration (ppm), and CO2 flux (g/m2/day) in the area appears as a point source (spot) and/or diffuses (halo) anomalies along the buried faults/fractures due to crustal leaks. The results revealed that Rn and CO2 concentrations in the soil gas show anomalous values at the specific positions in the Amik Basin. The trace of these anomalous values is coincident with the N-S trending DSF. CO2 is believed to act as a carrier for Rn gas. Based on the Rn and CO2 concentrations of soil gases, at least three gas components are required to explain the observed variations. In addition to the atmospheric component, two other gas sources can be recognized. One is the deep crust component, which exhibits high Rn and CO2 concentrations, and is considered the best indicator for the surface location of fault/fracture zones in the region. The other component is a shallower gas source with high Rn concentration and low CO2 concentration. Moreover, He isotopic compositions of representative samples vary from 0.94 to 0.99 Ra, illustrating that most samples have a soil air component and may have mixed with some crustal component, without significant input of the mantle component. Based on the repeated measurements at a few sites, soil gas concentrations at the same site were observed to be higher in 2014 than in 2013, which may be associated with the activity of the DSF in 2013–2014. This suggests that soil gas variations at fault zone are closely related to the local crustal stress, and hence are suitable for monitoring fault activities.
    Description: Published
    Description: 129–146
    Description: 6T. Variazioni delle caratteristiche crostali e precursori
    Description: JCR Journal
    Keywords: Dead Sea Fault ; Karasu Fault ; Amik Basin ; Radon ; Carbon Dioxide ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Complexity of the 2009 L'Aquila earthquake causative fault system (Abruzzi Apennines, Italy) and effects on the Middle Aterno Quaternary basin arrangement (2019)
    Elsevier
    Details
    Publication Date: 2021-06-15
    Description: An Mw 6.1, devastating earthquake, on April 6, 2009, struck the Middle Aterno Valley (Abruzzi Apennines, Italy) due to the activation of a poorly known normal fault system. Structural analysis of the fault population and investigation of the relationships with the Quaternary continental deposits through integrated field and laboratory techniques were conducted in order to reconstruct the long-term, tectono-sedimentary evolution of the basin and hypothesize the size of the fault segment. A polyphasic evolution of the Middle Aterno Valley is characterized by a conjugate, ∼E-W and ∼NS-striking fault system, during the early stage of basin development, and by a dip-slip, NW-striking fault system in a later phase. The old conjugate fault system controlled the generation of the largest sedimentary traps in the area and is responsible for the horst and graben structures within the basin. During the Early Pleistocene the E-W and NS system reactivated with dip-slip kinematics. This gave rise to intra-basin bedrock highs and a significant syn-tectonic deposition, causing variable thickness and hiatuses of the continental infill. Subsequently, since the end of the Early Pleistocene, with the inception of the NW-striking fault system, several NW-strands linked into longer splays and their activity migrated toward a leading segment affecting the Paganica-San Demetrio basin: the Paganica-San Demetrio fault alignment. The findings from this work constrain and are consistent with the subsurface basin geometry inferred from previous geophysical investigations. Notably, two major elements of the ∼E-W and ∼NS-striking faults likely act as transfer to the nearby stepping active fault systems or form the boundaries, as geometric complexities, that limit the Paganica-San Demetrio fault segment overall length to 19 ± 3 km. The resulting size of the leading fault segment is coherent with the extent of the 6 April 2009 L'Aquila earthquake causative fault. The positive match between the geologic long-term and coseismic images of the 2009 seismogenic fault highlights that the comprehensive reconstruction of the deformation history offers a unique contribution to the understanding faults seismic potential.
    Description: MIUR (Italian Ministry of Education, University and Research) project “FIRB Abruzzo - High-resolution analyses for assessing the seismic hazard and risk of the areas affected by the 6 April 2009 earthquake”, ref. RBAP10ZC8K_005 and RBAP10ZC8K_007, and by Agreement INGV-DPC 2012–2021
    Description: Published
    Description: 30-66
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Quaternary geology ; L'Aquila earthquake ; structural geology ; Middle Aterno Valley ; neotectonics ; active fault ; 04.04. Geology ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Contemporary stress field in the area of the 2016 Amatrice seismic sequence (central Italy) (2018)
    Details
    Publication Date: 2018-03-13
    Description: We update the last present-day stress map for Italy relatively to the area of 2016 Amatrice seismic sequence (central Italy) taking into account a large number of earthquakes occurred from August 24th to October 3rd, 2016. In particular in this paper, we discuss the new stress data from crustal earthquake focal mechanisms selecting those with Magnitude ≥ 4.0; at the same time, we revise the borehole data, analyze the stratigraphic profiles and the relative sonic logs in 4 deep wells located close to the Amatrice sequence along the Apennine belt and toward east along the Adriatic foredeep. From these data we consider the P-wave velocity trend with depth and estimate rock density following an empirical relationship. Then we calculate the overburden stress magnitude for each well. The new present-day stress indicators confirm the presence of prevalent normal faulting regime and better define the local stress field in the area, highlighting a slight rotation from NE-SW to ENE-WSW of extension. The analysis evidences that the lithostatic gradient gradually changes from ~26 MPa/km in the belt to less than 23 MPa/km along the Adriatic foredeep. Finally, at a depth of 5 km we estimate the vertical stress magnitude varying from 130 MPa to 114 moving from the Apennine belt to the Adriatic foredeep. Although the wells are very close each other they show different P wave velocities from the belt to the foredeep with values ~7km/s and ~4 km/s at 5 km depth, respectively.
    Description: Published
    Description: 1T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: present-day stress ; focal mechanism ; borehole data ; sonic velocity ; crustal density ; stress magnitude ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    IPSI 1.0, Database of Italian Present-day Stress Indicators (2018)
    Details
    Publication Date: 2018-03-23
    Description: Istituto Nazionale di Geofisica e Vulcanologia, Italy
    Description: Published
    Description: 1T. Deformazione crostale attiva
    Keywords: present-day stress ; borehole breakout ; earthquake focal mechanism ; fault ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: web product
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