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  • Articles  (46)
  • 04.07. Tectonophysics
  • Hydrothermal systems
  • 2020-2022  (46)
  • 1950-1954
  • 1945-1949
  • 1
    Publication Date: 2021-01-04
    Description: Following the 2004 seismic unrest at Tenerife and the 2011–2012 submarine eruption at El Hierro, the number of Global Navigation Satellite System (GNSS) observation sites in the Canary Islands (Spain) has increased, offering scientists a useful tool with which to infer the kinematics and present-day surface deformation of the Canary sector of the Atlantic Ocean. We take advantage of the common-mode component filtering technique to improve the signal-to-noise ratio of the velocities retrieved from the daily solutions of 18 permanent GNSS stations distributed in the Canaries. The analysis of GNSS time series spanning the period 2011–2017 enabled us to characterize major regions of deformation along the archipelago through the mapping of the 2D infinitesimal strain field. By applying the triangular segmentation approach to GNSS velocities, we unveil a variable kinematic behaviour within the islands. The retrieved extension pattern shows areas of maximum deformation west of Tenerife, Gran Canaria and Fuerteventura. For the submarine main seismogenic fault between Tenerife and Gran Canaria, we simulated the horizontal deformation and strain due to one of the strongest (mbLg 5.2) earthquakes of the region. The seismic areas between islands, mainly offshore Tenerife and Gran Canaria, seem mainly influenced by the regional tectonic stress, not the local volcanic activity. In addition, the analysis of the maximum shear strain confirms that the regional stress field influences the E–W and NE–SW tectonic lineaments, which, in accordance with the extensional and compressional tectonic regimes identified, might favour episodes of volcanism in the Canary Islands.
    Description: Published
    Description: 3297
    Description: 2T. Deformazione crostale attiva
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: GNSS time series ; kinematics and ground deformation ; Canary Islands ; 04.02. Exploration geophysics ; 04.03. Geodesy ; 04.07. Tectonophysics ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-01-19
    Description: To unravel how and where coseismic and interseismic deformation impacts the spatial and temporal patterns of rock uplift of the Lurestan sector of the Zagros Mountains, we performed an investigation of the large‐scale features of topography and river network coupled with 2‐D finite element modeling. Geomorphological analysis and constraints from parameters such as elevation, local relief, normalized channel steepness index (ksn), river longitudinal profiles, and transformed river profiles (chi plots) were used to unravel the time‐space distribution of vertical motions. Whereas the much longer timescale over which topography grows and/or rivers respond to tectonic or climatic perturbations with respect to even multiple seismic cycles, the outputs of the finite element model yield fundamental information on the source of the late part of the spatiotemporal evolution of surface uplift recorded by the geomorphology. Model outputs shed new light into the processes controlling relief evolution in an actively growing mountain belt underlain by a major blind thrust. The outputs illustrate how coseismic slip controls localized uplift of a prominent topographic feature—the Mountain Front Flexure—located above the main upper crustal ramp of the principal basement thrust fault of the region, while continuous displacement along the deeper, aseismic portion of the same basement fault controls generalized uplift of the whole crustal block located farther to the NE, in the interior of the orogen.
    Description: Published
    Description: e2020TC006402
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Morphotectonic analysis ; Finite element modeling ; interseismic deformation ; coseismic deformation ; frontal topographic feature ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Elsevier B.V.
    Publication Date: 2021-02-01
    Description: In supervised classification, we search criteria allowing us to decide whether a sample belongs to a certain class of patterns. The identification of such decision functions is based on examples where we know a priori to which class they belong. The distinction of seismic signals, produced from earthquakes and nuclear explosions, is a classical problem of discrimination using classification with supervision. We move on from observed data—signals originating from known earthquakes and nuclear tests—and search for criteria on how to assign a class to a signal of unknown origin. We begin with Principal Component Analysis (PCA) and Fisher's Linear Discriminant Analysis (FLDA), identifying a linear element separating groups at best. PCA, FLDA, and likelihood-based approaches make use of statistical properties of the groups. Considering only the number of misclassified samples as a cost, we may prefer alternatives, such as the Multilayer Perceptrons (MLPs). The Support Vector Machines (SVMs) use a modified cost function, combining the criterion of the minimum number of misclassified samples with a request of separating the hulls of the groups with a margin as wide as possible. Both SVMs and MLPs overcome the limits of linear discrimination. A famous example for the advantages of the two techniques is the eXclusive OR (XOR) problem, where we wish to form classes of objects having the same parity—even, e.g., (0,0), (1,1) or odd, e.g., (0,1), (1,0). MLPs and SVMs offer effective methods for the identification of nonlinear decision functions, allowing us to resolve classification problems of any complexity provided the data set used during earning is sufficiently large. In Hidden Markov Models (HMMs), we consider observations where their meaning depends on their context. Observations form a causal chain generated by a hidden process. In Bayesian Networks (BNs) we represent conditional (in)dependencies between a set of random variables by a graphical model. In both HMMs and BNs, we aim at identifying models and parameters that explain observations with a highest possible degree of probability.
    Description: Published
    Description: 33-85
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; supervised learning ; Support Vector Machines ; Multilayer Perceptrons ; Hidden Markov Models ; Bayesian Networks ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 4
    Publication Date: 2021-02-01
    Description: Patterns and objects are described by a variety of characteristics, namely features and feature vectors. Features can be numerical, ordinal, and categorical. Patterns can be made up of a number of objects, such as in speech processing. In geophysics, numerical features are the most common ones and we focus on those. The choice of appropriate features requires a priori reasoning about the physical relation between patterns and features. We present strategies for feature identification and procedures suitable for pattern recognition. In time series analysis and image processing, the direct use of raw data is not feasible. Procedures of feature extraction, based on locally encountered characteristics of the data, are applied. Here we present the problem of delineating segments of interest in time series and textures in image processing. In transformations, we “translate” our raw data to a form suitable for learning. In Principal Component Analysis, we rotate the original features to a system of uncorrelated variables, limiting redundancy. Independent Component Analysis follows a similar strategy, transforming our data into variables independent of each other. Fourier transform and wavelet transform are based on the representation of the original data as a series of basis functions—sines and cosines or finite-length wavelets. Redundancy reduction is achieved considering the contributions of the single basis functions. Even though a large number of features help to solve a classification problem, feature vectors with high dimensions pose severe problems. Besides the computational burden, we encounter problems known under the term “curse of dimensionality.” The curse of dimensionality entails the necessity of feature selection and reduction, which includes a priori considerations as well as redundancy reduction. The significance of features may be evaluated with tests, such as Student’s t or Hotelling's T2, and, in more complex problems, with cross-validation methods.
    Description: Published
    Description: 3-13
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; objects ; features ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 5
    Publication Date: 2021-03-08
    Description: The NEAM Tsunami Hazard Model 2018 (NEAMTHM18) is a probabilistic hazard model for tsunamis generated by earthquakes. It covers the coastlines of the North-eastern Atlantic, the Mediterranean, and connected seas (NEAM). NEAMTHM18 was designed as a three-phase project. The first two phases were dedicated to the model development and hazard calculations, following a formalized decision-making process based on a multiple-expert protocol. The third phase was dedicated to documentation and dissemination. The hazard assessment workflow was structured in Steps and Levels. There are four Steps: Step-1) probabilistic earthquake model; Step-2) tsunami generation and modeling in deep water; Step-3) shoaling and inundation; Step-4) hazard aggregation and uncertainty quantification. Each Step includes a different number of Levels. Level-0 always describes the input data; the other Levels describe the intermediate results needed to proceed from one Step to another. Alternative datasets and models were considered in the implementation. The epistemic hazard uncertainty was quantified through an ensemble modeling technique accounting for alternative models’ weights and yielding a distribution of hazard curves represented by the mean and various percentiles. Hazard curves were calculated at 2,343 Points of Interest (POI) distributed at an average spacing of ∼20 km. Precalculated probability maps for five maximum inundation heights (MIH) and hazard intensity maps for five average return periods (ARP) were produced from hazard curves. In the entire NEAM Region, MIHs of several meters are rare but not impossible. Considering a 2% probability of exceedance in 50 years (ARP≈2,475 years), the POIs with MIH 〉5 m are fewer than 1% and are all in the Mediterranean on Libya, Egypt, Cyprus, and Greece coasts. In the North-East Atlantic, POIs with MIH 〉3 m are on the coasts of Mauritania and Gulf of Cadiz. Overall, 30% of the POIs have MIH 〉1 m. NEAMTHM18 results and documentation are available through the TSUMAPS-NEAM project website (http://www.tsumaps-neam.eu/), featuring an interactive web mapper. Although the NEAMTHM18 cannot substitute in-depth analyses at local scales, it represents the first action to start local and more detailed hazard and risk assessments and contributes to designing evacuation maps for tsunami early warning.
    Description: The NEAMTHM18 was prepared in the framework of the European Project TSUMAPS-NEAM (http://www.tsumaps-neam.eu/) funded by the mechanism of the European Civil Protection and Humanitarian Aid Operations with grant no. ECHO/SUB/2015/718568/PREV26 (https://ec.europa.eu/echo/funding-evaluations/financing-civil-protection-europe/selected-projects/probabilistic-tsunami-hazard_en). The work by INGV authors also benefitted from funding by the INGV-DPC Agreement 2012-2021 (Annex B2).
    Description: Published
    Description: 616594
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: 1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunami
    Description: 2SR TERREMOTI - Gestione delle emergenze sismiche e da maremoto
    Description: 3SR TERREMOTI - Attività dei Centri
    Description: 5SR TERREMOTI - Convenzioni derivanti dall'Accordo Quadro decennale INGV-DPC
    Description: 3IT. Calcolo scientifico
    Description: 4IT. Banche dati
    Description: JCR Journal
    Keywords: probabilistic tsunami hazard assessment ; earthquake-generated tsunami ; hazard uncertainty analysis ; ensemble modeling ; maximum inundation height ; NEAM ; 05.08. Risk ; 03.02. Hydrology ; 04.06. Seismology ; 04.07. Tectonophysics ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2021-07-13
    Description: The millimetre accuracy of Synthetic Aperture Radar (SAR) measurements and related multi-temporal data analyses provide fundamental information on surface displacements caused by strong earthquakes. The multi-temporal analysis of SAR interferometry data allows for the geometry, kinematics and temporal behaviour of earthquake-generating faults to be better constrained, and is being acknowledged as a promising technique in the field of earthquake precursors. We used SAR data obtained by multi-temporal interferometric techniques such as Permanent Scatterers (PS) interferometry for the investigation of pre- to post-seismic ground displacements in the region struck by theMw 6.3, 2009 L’Aquila earthquake.We analysed Europen Remote Sensing (ERS) and Envisat PS-datasets from ascending and descending orbits, and COSMO-SkyMed PS-datasets from descending orbit, collectively covering a 〉 20 year long time span. On a yearly scale, a reversal of motions that affected the hanging-wall and footwall blocks of the earthquake-generating fault is detected. In particular, the hanging-wall block is characterized by pre-seismic uplift – which we document as being independent of any hydrological control – and eastward horizontal motion for about six years, followed by subsidence and westward motion (starting six to eight months prior to the earthquake). We suggest that such a ground displacement pattern may represent an earthquake precursor signal.
    Description: Published
    Description: jgs2020-016
    Description: 2T. Deformazione crostale attiva
    Description: 7T. Variazioni delle caratteristiche crostali e "precursori"
    Description: JCR Journal
    Keywords: PsInSAR ; Earthquake Precursor ; L'Aquila earthquake ; Ground displacement ; 04.07. Tectonophysics ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2021-01-04
    Description: The Calabrian Arc subduction, southern Italy, is a critical structural element in the geodynamic evolution of the central Mediterranean basin. It is a narrow, northwestdipping slab bordered to the southwest by the Alfeo Fault System (AFS) and to the northeast by a gradual transition to a collision. We used a dense set of two-dimensional high-penetration (up to 12 s) multichannel seismic reflection profiles to build a threedimensional model that spans the AFS for over 180 km of its length. We find that the AFS is made up of four deep-seated major blind segments that cut through the lower plate, offset the subduction interface, and only partially propagate upward across the accretionary wedge in the upper plate. These faults evolve with a scissor-like mechanism (mode III of rupture propagation). The shallow part of the accretionary wedge is affected by secondary deformation features well aligned with the AFS at depth but also mechanically decoupled from it. Despite the decoupling, the syn-tectonic Pliocene-Holocene deposits that fill in the accommodation space generated by the AFS activity at depth, constrain the age of inception of the AFS and allows us to estimate its throw and propagation rates. The maximum throw value is 6,000 m in the NW sector and decreases to the SE. Considering the age of faulting, the fault throw rate decreases accordingly from 2.31 mm/yr to 1 mm/yr. The propagation rate decreases from 62 mm/yr to 15 mm/yr during the Pliocene-Pleistocene, suggesting that also the Calabrian subduction process should have slowed down accordingly. The detailed spatial and temporal reconstruction of this type of faults can reveal necessary information about the evolution of subduction systems.
    Description: Published
    Description: id 107
    Description: 2T. Deformazione crostale attiva
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Keywords: tear fault ; fault propagation ; decoupling ; subduction ; Calabrian Arc ; Italy ; 04.04. Geology ; 04.02. Exploration geophysics ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    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)
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  • 9
    Publication Date: 2021-01-19
    Description: Using an analyticalmethodology taking into account heat flowdensity data, frictional heating, temperature variations due to the re-equilibrated conductive state after thrusting and geological constrains, we calculated surface heat flow, geotherms and isotherms along a balanced and restored regional geological cross-section. Our results highlight the impact of frictional heating produced by thrusts on the thermal structure of the study area, leading to a raising of the isotherms both in the inner Albanides to the E and in the Adriatic sector offshore. Minimum values of Qs in the surroundings of Tirana and the reconstructed 2D thermal structure suggest less favorable conditions for exploitation of geothermal energy, besides the direct use (Borehole Heat Exchanger-Geothermal Heat Pump systems). Nevertheless, the occurrence of the “Kruja geothermal zone”, partially overlapping this area and including hot springmanifestations, emphasize the structural control in driving hot fluids to the surface with respect to the regional thermal structure.
    Description: Published
    Description: 6028
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: balanced cross-sections ; thermal modeling ; fold and thrust belts ; frictional heating ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2021-01-19
    Description: The Zagros thrust belt is a large orogenic zone located along the southwest region of Iran. To obtain a better knowledge of this important mountain chain, we elaborated the first 3-D model reproducing the thermal structure of its northwestern part, i.e., the Lurestan arc. This study is based on a 3-D structural model obtained using published geological sections and available information on the depth of the Moho discontinuity. The analytical calculation procedure took into account the temperature variation due to: (1) The re-equilibrated conductive state after thrusting, (2) frictional heating, (3) heat flow density data, and (4) a series of geologically derived constraints. Both geotherms and isotherms were obtained using this analytical methodology. The results pointed out the fundamental control exerted by the main basement fault of the region, i.e., the Main Frontal Thrust (MFT), in governing the thermal structure of the crust, the main parameter being represented by the amount of basement thickening produced by thrusting. This is manifested by more densely spaced isotherms moving from the southwestern foreland toward the inner parts of orogen, as well as in a lateral variation related with an along-strike change from a moderately dipping crustal ramp of the MFT to the NW to a gently dipping crustal ramp to the SE. The complex structural architecture, largely associated with late-stage (Pliocene) thick-skinned thrusting, results in a zone of relatively high geothermal gradient in the easternmost part of the study area. Our thermal model of a large crustal volume, besides providing new insights into the geodynamic processes affecting a major salient of the Zagros thrust belt, may have important implications for seismotectonic analysis in an area recently affected by a Mw = 7.3 earthquake, as well as for geothermal/hydrocarbon exploration in the highly perspective Lurestan region.
    Description: Published
    Description: 2140
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: active tectonics ; heat flow ; 3-D thermal modelling ; thermal structure ; temperature profile ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2021-05-12
    Description: In case of moderate to strong earthquakes (generally for M 〉 5.5), coseismic slip along a fault can reach directly the ground surface and produce surface faulting. Although scarcely considered in the Italian legislation, surface faulting hazard can have a relevant societal impact because it exposes to substantial risk urban areas and/or important infrastructures, facilities and critical lifelines that are settled or planned in coincidence of an active and capable fault trace. In this paper we present a case study from the area hit by the Mw 6.1 April 6, 2009 L’Aquila earthquake (Central Italy), where buildings and critical lifelines located across or near the coseismic surface ruptures suffered significant damage. High resolution (1 m) LiDAR topographic data contributed to the assessment of surface faulting hazard through a better imaging of the surface geometrical arrangement of the earthquake causative fault and through the analysis of the spatial relationships between active fault splays and critical lifelines and infrastructures.
    Description: Published
    Description: 345-347
    Description: 2T. Deformazione crostale attiva
    Description: N/A or not JCR
    Keywords: LIDAR ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2021-05-12
    Description: The accuracy of the millimetre-scale measurements made so far by the SAR systems, as well as the multi-temporal analysis methodologies, have provided impressive images of surface displacements in areas affected by strong earthquakes, and contributed to constrain the geometric and kinematic features of earthquake generating faults. The multi-temporal analysis of InSAR data is also being acknowledged as promising for the search of earthquake precursors. We have applied the multi-temporal PS-InSAR technique to the detection of pre- to post-seismic ground displacements in the region struck by the normal faulting 2009 L’Aquila earthquake. We have used ERS and ENVISAT PS-data sets from both ascending and descending orbits, covering a 20-year long time span. On the yearly-scale, we have identified a pre-seismic displacement pattern, which consists of opposite vertical motions that have affected the blocks in the hanging wall and footwall of the structure that is recognised as the surface trace of the earthquake-generating fault. In particular, we have highlighted a pre-seismic uplift for 4-5 years followed by subsidence (starting 6-8 months prior to the earthquake) of the hanging wall block, coeval to opposite vertical motions of the footwall block. We suggest that such a displacement pattern may represent an earthquake precursor signal.
    Description: Published
    Description: 41-56
    Description: 2T. Deformazione crostale attiva
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: PS-InSAR ; MW 6.3 L’Aquila earthquake ; ground deformation ; pre-seismic ; earthquake precursor ; central Apennines ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    Frontiers
    In:  Argnani, A. (2020). Commentary: deformation and fault propagation at the lateral termination of a subduction zone: the Alfeo Fault system in the calabrian Arc, southern Italy. Front. Earth Sci. 8, 602506. doi:10.3389/feart.2020.602506
    Publication Date: 2021-05-12
    Description: Argnani (2020) raised concerns about our interpretation of the Alfeo Fault System (AFS) as a lithospheric tear bounding the Calabrian Arc (Maesano et al., 2020). Some of these concerns arise from elements overlooked by Argnani (2020); others are marginally related to our work; none of them implies possible changes in our results in the absence of newer data. We briefly discuss these issues in the following.
    Description: Published
    Description: 644544
    Description: 2T. Deformazione crostale attiva
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Keywords: lithospheric tear fault ; seismic stratigraphy ; Calabrian subduction ; Ionian Sea ; Italy ; decoupling ; fault propagation ; Calabrian Arc ; 04.04. Geology ; 04.07. Tectonophysics ; 04.02. Exploration geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2021-02-01
    Description: In this chapter, we deal with a posterior analysis of supervised and unsupervised learning techniques. Concerning supervised learning, we discuss methods of cross-validation and assessment of uncertainty of tests by means of the “Receiver Operation Curve” and the “Kappa-Statistics.” We show the importance of appropriate target information. Furthermore, features are critical; when they are not properly chosen, they fail to describe objects in a unique way. A critical attitude is mandatory to validate the success of an application. A high score of success does not automatically mean that a method is truly effective. At the same time, users should not despair when the desired success is not achieved. A posteriori analysis on the reasons for an apparent failure may provide useful insights into the problem. Targets may not be appropriately defined, features can be inadequate, etc. Problems can be often fixed by adjusting a few choices; sometimes a change of strategy may be necessary to improve results. In unsupervised learning, we ask whether the structures revealed in the data are meaningful. Cluster analysis offers rules giving formal answers to this question; however, such rules are not generally applicable. In some cases, a heuristic approach may be necessary.
    Description: Published
    Description: 237-259
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; a posteriori analysis ; supervised learning ; unsupervised learning ; cross validation ; assessment of uncertainty ; Receiver Operation Curve ; Kappa-Statistics ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 15
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    Elsevier B.V.
    Publication Date: 2021-02-01
    Description: Unsupervised learning is based on the definition of an appropriate metrics defining the similarity of patterns. On the basis of the metrics, we form groups or clusters of patterns following various strategies. In partitioning cluster analysis, we form disjoint clusters. Being faced with data, where clusters still exhibit heterogeneities or subclusters, we may adopt the strategy of hierarchical clustering, which leads to the generation of the so-called dendrograms. In the partitioning strategy, we choose a priori the number of clusters we wish to form, whereas in the hierarchical strategy, the number of clusters depends on the resolution we want to have. Density-based clustering considers local structures of a data set. We consider a unit volume in our data space and derive the density of samples within this volume. Moving toward neighboring volumes, we verify whether the number of samples has dropped below a threshold. If this is the case, we identify a heterogeneity, otherwise we join the neighboring volumes to a common cluster. Self-Organizing Maps (SOMs) provide a way of representing multidimensional data in much lower dimensional spaces than the original data set. The process of reducing the dimensionality of vectors is essentially a data compression technique known as vector quantization. The SOM technique creates a network that stores information in a way that it maintains the topological relationships within the patterns of the data set. Each node of the network represents a number of patterns. Assigning a color code to the nodes, the representation of pattern characteristics with high-dimensional feature vectors becomes extremely effective.
    Description: Published
    Description: 87-124
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; unsupervised learning ; cluster analysis ; Density-based clustering ; Self-Organizing Maps ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 16
    Publication Date: 2021-02-01
    Description: This chapter demonstrates how Unsupervised Learning can be applied in Geophysics. It starts with an example of clustering seismic spectra obtained on Stromboli volcano. K-means clustering as well as clustering using the Adaptive Criterion are applied. The latter criterion is preferred as it better matches the statistical characteristics of the data. Clusters show close relation to the state of volcanic activity. Density based clustering reveals groups whose hulls can be of irregular shape. This makes the method attractive, among others, for the identification of structural elements in geology, which often do not have a simple geometry. An example application is discussed considering the distribution of earthquake locations on Mt Etna, which clearly evidence structures already identified by other, independent evidences. Using SOM we aim at data reduction and effective graphical visualization. In an example for climate data we demonstrate the application of SOM for zoning purposes. Besides, the temporal evolution of spectral seismic data recorded on Mt Etna can be effectively monitored using SOM. We further illustrate the use of SOM for directional data, which can be handled best using a toroidal sheet geometry. We discuss this using a data set of seismic moment tensors of Mediterranean earthquakes.
    Description: Published
    Description: 189-234
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; unsupervised learning ; Density based clustering ; Stromboli ; earthquakes ; volcanic activity ; structural data ; seismic moment tensors ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Elsevier B.V.
    Publication Date: 2021-02-01
    Description: In this chapter, we present scripts and programs that accompany this book. Five MATLAB scripts regard simple examples related to supervised learning, that is, linear discrimination, the perceptron, support vector machines, and hidden Markov models. Seven scripts are devoted to unsupervised learning, such as K-means and fuzzy clustering, agglomerative clustering, density-based clustering, and clustering of patterns where features are correlated. These scripts provide a starting point for the reader, who can adjust and modify the codes with respect to proper needs. Besides, we provide sources and executables of programs that can be readily applied to larger and more complex datasets. These programs regard supervised learning using multilayerperceptron and support vector machines. KKAnalysis is a toolbox for unsupervised learning and offers various options of clustering and the use of self-organizing maps. The programs offer graphical user interfaces (GUI) to facilitate their use and create both graphical and alphanumeric output that can be used in further processing steps. The programs come along with real-world datasets that are also discussed in the example applications presented in various chapters of the book. Other propaedeutic material can be found in a folder called “miscellaneous.”
    Description: Published
    Description: 261-313
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; software manuals ; MATLAB scripts ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
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  • 18
    Publication Date: 2021-01-18
    Description: Nel maggio 2012, due terremoti di magnitudo moderata, seguiti da un importante sciame sismico, hanno coinvolto il settore orientale della Pianura Padana. In questa nota si vuole illustrare in modo sintetico il complesso sistema di strutture tettoniche che si trovano sotto i nostri piedi e che, nel loro insieme, costituiscono il prolungamento settentrionale dell’orogene appenninico attualmente sepolto e ‘nascosto’ dalle coltri alluvionali della Pianura Padana. Il settore più esterno di questa catena montuosa è rappresentato da un sistema di sovrascorrimenti disposti a geometria arcuata: il cosiddetto Arco Ferrarese. Gli eventi sismici del maggio 2012 ed alcuni dei maggiori terremoti storici che hanno colpito Ferrara nei secoli precedenti sono stati causati proprio dalla riattivazione di alcuni segmenti appartenenti a tale complesso sistema deformativo. Quando si verificherà il prossimo evento e dove esattamente non possiamo prevederlo con esattezza ma, visto il contesto tettonico e geodinamico, il fenomeno si ripeterà certamente nel futuro ed è pertanto opportuno fare prevenzione.
    Description: Published
    Description: 161-177
    Description: 3T. Sorgente sismica
    Keywords: 04.07. Tectonophysics
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  • 19
    Publication Date: 2021-01-26
    Description: Geophysical and geochemical networks are routinely deployed on active volcanoes to observe and monitor unrest periods. However, changes of the physical parameters with time are related to either magma/fluid movement or variations occurring in the hydrothermal systems hosted in the volcanic edifice. Here we use four years of ambient seismic noise recorded at the Stromboli volcano to reconstruct its shallow structure using the ambient noise cross-correlation method. At the same time, we detect temporal variations of the seismic velocities associated with the volcanic activity. We correlated the most reliable variations both in space and in time with other seismic and geochemical information in order to identify lapses of time of general unrest. We also implemented a method to enhance their spatial visualization for the interpretation. We found that the spatial mapping of the seismic velocity temporal variations obtained processing the data at high frequency (1.5–2.5 Hz) match with the location of the main hydrothermal reservoirs of the volcano. This suggests that there is a relationship between volcanic activity and hydrothermal areas that can be detected and monitored for a better understanding of the volcanic phenomena
    Description: Published
    Description: 107177
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: Hydrothermal systems ; Stromboli volcano
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  • 20
    Publication Date: 2021-02-15
    Description: This chapter presents applications of supervised learning in various geophysical disciplines, being them seismology, geodesy, magnetism, and others. For all examples, we provide a brief introduction to the geophysical background. Practical aspects, such as normalization issues and feature selection, are discussed. A posteriori considerations shed light on the geophysical problem, such as the importance of model parameters in regression, the possible nonuniqueness in inversion, and flaws in the definition of targets. We demonstrate multilayer perceptrons (MLPs) as classifiers of seismic waveforms. Besides, we show how the use of MLP is straightforward in the context of inversion of various kinds of data, for example, seismic, geodetic, and magnetic. Regression with MLP is applied to magnetotelluric and seismic data. Multiclass classification with support vector machine (SVM) is discussed for infrasound waveforms and volcanic rocks using geochemical characteristics. We introduce the use of SVM in the context of regression, which is formally less immediate than for MLP, but yields good results. An example deals with empirical ground motion estimation during earthquakes. In hidden Markov models and Bayesian networks one considers the interrelation between observations rather than single patterns. We show their benefits in various applications, from seismic waveform classification aimed at the forecast of volcanic unrest up to their use in tsunami early-warning systems.
    Description: Published
    Description: 127-187
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: pattern recognition ; supervised learning ; multilayer perceptrons ; seismic data ; magnetotelluric data ; infrasound waveforms ; volcanic rocks ; geochemical characteristics ; 04.04. Geology ; 04.06. Seismology ; 04.07. Tectonophysics ; 04.08. Volcanology ; 05.04. Instrumentation and techniques of general interest
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  • 21
    Publication Date: 2021-04-12
    Description: This study presents a preliminary review of the instrumental seismicity of the Norcia-Amatrice area (central Italy) during the years preceding the on-going seismic sequence started on August 24th 2016 with a Mw 6.0 earthquake and occurred close to Accumoli village; a Mw 5.9 happened on October 26th, two months later, 3 km West of Visso and finally a Mw 6.5 on October 30th, 6 km North of Norcia, the largest earthquake recorded in Italy since the Mw 6.9 1980 Irpinia event. The clustering of earthquakes in time and space has been investigated by analysing seismic catalogs for the period 1981-2016, the CMT (Centroid Moment Tensor) catalogue and the TDMT (Time Domain Moment Tensor) solutions. The seismicity of this region is characterized by different types of activity: single events, minor sequences and swarms with hypocenters within the upper 15 km of the crust. A minor sequence on March 2007 (with maximum Mw 3.9 not followed by significant seismicity) affected the area East of Norcia close to the August 24th Mw 5.4 and close to the October 30th Mw 6.5. In the central area, near Accumoli, and in the southern sector close to Amatrice, minor seismic sequences occurred on February 2014 with a Ml 3.5 mainshock and on November 2013 with a Mw3.7 mainshock, respectively. We integrated hypocentral locations and fault plane solutions to give a first look at the main features of the instrumental seismicity compared to the present seismic sequence in order to relate seismicity patterns to the seismogenic structures of the target area.
    Description: Published
    Description: 1-8
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: 04.07. Tectonophysics
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  • 22
    Publication Date: 2021-05-12
    Description: InSAR images allow to detect the coseismic deformation, delimiting the epicentral area where the larger displacement has been concentrated. By inspecting the InSAR fringe patterns it is commonly recognized that, for dip-slip faults, the most deformed area is elliptical, or quadrilobated for strike-slip faults. This area coincides with the surface projection of the volume coseismically mobilized in the hanging wall of thrusts and normal faults, or the crustal walls adjacent to strike-slip faults. In the present work we analyzed a dataset of 32 seismic events, aiming to compare the deformation fields in terms of shape, spatial extents, and amount of deformed rock volumes, and the corresponding earthquake type and magnitudes. The dimension of the deformed area detected by InSAR scales with the magnitude of the earthquake, and we found that for M ≥ 6 is always larger than 100 km2, increasing to more than 550 km2 for M ≈ 6.5. Moreover, the comparison between InSAR and Peak Ground Accelerations documents the larger shaking within the areas suffering higher vertical deformation. As well established, the seismic epicenter rarely coincides with the area of larger shaking. Instead, the higher macro- seismic intensity often corresponds to the area of larger vertical displacement (either downward or upward), apart local site amplification effects. Outside this area, the vertical displacement is drastically lower, determining the strong attenuation of seismic waves and the decrease of the peak ground acceleration in the surrounding far- field area. Indeed, the segment of the activated fault constrains the area where the vertical oscillations are larger, allowing the contemporaneous maximum freedom degree of the crustal volume affected by horizontal maximum shaking, i.e., the near-field or epicentral area; therefore, the epicentral area and volume are active, i.e., they coseismically move and are contemporaneously crossed by seismic waves (active volume and surface active domain) where trapped waves and constructive interference are expected, whereas the surrounding far-field area is mainly fixed and passively crossed by seismic waves (passive volume and surface passive domain). All these considerations point out that InSAR images of areas affected by earthquakes are a powerful tool representing the fingerprint of the epicentral area where the largest shaking has taken place during an earthquake. Seismic hazard assessments should primarily rely on the expected future active domains.
    Description: Published
    Description: 103667
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Keywords: InSAR coseismic vertical deformation ; Constructive waves inferference ; Seismic hazard assessment ; Earthquake epicentral area ; Near-field active domain ; 04.07. Tectonophysics
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  • 23
    Publication Date: 2021-06-01
    Description: When sedimentation rates overtake tectonic rates, the detection of ongoing tectonic deformation signatures becomes particularly challenging. The Northern Apennines orogen is one such case where a thick Plio-Pleistocene foredeep sedimentary cover blankets the fold-and-thrust belt, straddling from onshore (Po Plain) to offshore (Adriatic Sea), leading to subtle or null topo-bathymetric expression of the buried structures. The seismic activity historically recorded in the region is moderate; nonetheless, seismic sequences nearing magnitude 6 punctuated the last century, and even some small tsunamis were reported in the coastal locations following the occurrence of offshore earthquakes. In this work, we tackled the problem of assessing the potential activity of buried thrusts by analyzing a rich dataset of 2D seismic reflection profiles and wells in a sector of the Northern Apennines chain located in the near-offshore of the Adriatic Sea. This analysis enabled us to reconstruct the 3D geometry of eleven buried thrusts. We then documented the last 4 Myr slip history of four of such thrusts intersected by two high-quality regional cross-sections that were depth converted and restored. Based on eight stratigraphic horizons with well-constrained age determinations (Zanclean to Middle Pleistocene), we determined the slip and slip rates necessary to recover the observed horizon deformation. The slip rates are presented through probability density functions that consider the uncertainties derived from the horizon ages and the restoration process. Our results show that the thrust activation proceeds from the inner to the outer position in the chain. The slip history reveals an exponential reduction over time, implying decelerating slip-rates spanning three orders of magnitudes (from a few millimeters to a few hundredths of millimeters per year) with a major slip-rate change around 1.5 Ma. In agreement with previous works, these findings confirm the slip rate deceleration as a widespread behavior of the Northern Apennines thrust faults.
    Description: Published
    Description: 664288
    Description: 1T. Struttura della Terra
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Keywords: active fault ; buried thrust ; slip rate ; trishear ; restoration ; sediment decompaction ; Northern Apennines ; Italy ; 04.02. Exploration geophysics ; 04.04. Geology ; 04.07. Tectonophysics
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  • 24
    Publication Date: 2021-05-31
    Description: We analyze the gross crustal structure of the Atlantic Ocean passive continental margins from north to the south, comparing eleven sections of the conjugate margins. As a general result, the western margins show a sharper continental-ocean transition with respect to the eastern margins that rather show a wider stretched and thinner margin. The Moho is in average about 5.7 ±1 dipping toward the interior of the continent on the western side, whereas it is about 2.7 ±1 in the eastern margins. Moreover, the stretched continental crust is on average 244 km wide on the western side, whereas it is up to about 439 km on the eastern side of the Atlantic. This systematic asymmetry reflects the early stages of the diachronous Mesozoic to Cenozoic continental rifting, which is inferred as the result of a polarized westward motion of both western and eastern plates, being Greenland, Northern and Southern Americas plates moving westward faster with respect to Scandinavia, Europe and Africa, relative to the underlying mantle.
    Description: Published
    Description: 101205
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Passive continental margin ; Westward drift of the lithosphere ; Moho dip Continental-ocean transition ; Asymmetric rift ; 04.07. Tectonophysics
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  • 25
    Publication Date: 2021-09-22
    Description: We document the tectonic and metamorphic evolution of thrust nappes of the eastern island of Elba. The area exposes a natural cross section of the Northern Apennines hinterland, from the metamorphic basement units to the overlying continent- and ocean-derived nappes. We integrated mapping, analysis of structures and microstructures, and the interpretation of drill core logs with lithostratigraphic, metamorphic, and geochronological constraints, producing a novel geological map of eastern Elba (1:5'000 scale). We show that the area experienced polyphase Oligocene - Pliocene contractional tectonics marked by in-sequence and out-of-sequence thrusting accompanied by folding and overprinted by faulting in the Pliocene. Magmatism occurred during contraction with post-magmatic thrusting ultimately coupling HP-LT and LP-HT units. Drill core logs allow for the first time the reconstruction of the N-dipping character of the Zuccale Fault, which represents the youngest (late Miocene - early Pliocene) large-scale structure in the area.
    Description: Published
    Description: 519-532
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Geological Map ; Elba Island ; Northern Apennines ; Tectonic evolution ; 04.04. Geology ; 04.07. Tectonophysics
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  • 26
    Publication Date: 2021-09-20
    Description: Lusi is a sediment-hosted geothermal system relentlessly erupting since May 2006 in the East Java back-arc sedimentary basin. Lusi provides the unprecedented opportunity to study the development of the early phases of a new-born piercement structure and its impact on society. In order to investigate the shallow plumbing system of this large-scale eruption, we deployed a pool of 25 IRIS V-Fullwavers to conduct a 3D deep electrical resistivity tomography extending over ∼15 km2 around the eruption site. The inverted data reveal the structure of the subsided area hosting the region where a mix of groundwater, mud breccia, hydrocarbons and boiling hydrothermal fluids are stored. Our investigation also points out the link between a well-developed fault system and the upwelling of the deep-seated fluids that initiated, and still drive, the development of the new-born Lusi eruption.
    Description: Published
    Description: e2021GL092632
    Description: 7A. Geofisica per il monitoraggio ambientale
    Description: JCR Journal
    Keywords: Extensive 3D deep electrical resistivity tomography ; Lusi Eruption Site in East Java ; 04.02. Exploration geophysics ; 04.07. Tectonophysics
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  • 27
    Publication Date: 2021-08-31
    Description: We make a thorough review of geological and seismological data on the long-lived Schio-Vicenza Fault System (SVFS) in northern Italy and present for it a geodynamic and seismotectonic interpretation. The SVFS is a major and high-angle structure transverse to the mean trend of the eastern Southern Alps fold-and-thrust belt, and the knowledge of this structure is deeply rooted in the geological literature and spans more than a century and a half. The main fault of the SVFS is the Schio-Vicenza Fault (SVF), which has a significant imprint in the landscape across the eastern Southern Alps and the Veneto-Friuli foreland. The SVF can be divided into a northern segment, extending into the chain north of Schio and mapped up to the Adige Valley, and a southern one, coinciding with the SVF proper. The latter segment borders to the east the Lessini Mountains, Berici Mountains and Euganei Hills block, separating this foreland structural high from the Veneto-Friuli foreland, and continues southeastward beneath the recent sediments of the plain via the blind Conselve–Pomposa fault. The structures forming the SVFS have been active with different tectonic phases and different styles of faulting at least since the Mesozoic, with a long-term dip-slip component of faulting well defined and, on the contrary, the horizontal component of the movement not being well constrained. The SVFS interrupts the continuity of the eastern Southern Alps thrust fronts in the Veneto sector, suggesting that it played a passive role in controlling the geometry of the active thrust belt and possibly the current distribution of seismic release. As a whole, apart from moderate seismicity along the northern segment and few geological observations along the southern one, there is little evidence to constrain the recent activity of the SVFS. In this context, the SVFS, and specifically its SVF strand, has accommodated a different amount of shortening of adjacent domains of the Adriatic (Dolomites) indenter by internal deformation produced by lateral variation in strength, related to Permian–Mesozoic tectonic structures and paleogeographic domains. The review of the historical and instrumental seismicity along the SVFS shows that it does not appear to have generated large earthquakes during the last few hundred years. The moderate seismicity points to a dextral strike-slip activity, which is also corroborated by the field analysis of antithetic Riedel structures of the fault cropping out along the northern segment. Conversely, the southern segment shows geological evidence of sinistral strike-slip activity. The apparently conflicting geological and seismological data can be reconciled considering the faulting style of the southern segment as driven by the indentation of the Adriatic plate, while the opposite style along the northern segment can be explained in a sinistral opening “zipper” model, where intersecting pairs of simultaneously active faults with a different sense of shear merge into a single fault system.
    Description: Published
    Description: 1967-1986
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Inherited faults ; Fold and thrust belt ; Transverse structures ; Strike-slip faults ; Southern Alps ; 04.07. Tectonophysics ; 04.04. Geology
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  • 28
    Publication Date: 2020-09-09
    Description: The identification and characterization of seismogenic structures in southwestern Sicily is an open debate both for the geological-structural complexity of this sector and the scarce seismicity as well. In addition, clear morphological evidence of tectonic structures is limited. Besides the geophysical methods, the study of the spatial distribution of soil CO2 flux is a valid methodology to investigate the position and geometry of buried active faults. Indeed, active tectonic structures are channels with high permeability through which deep fluids can migrate toward the atmosphere. Therefore, the alignment of high degassing areas can reveal the presence of preferential ways of rising fluids (i.e. faults). We applied this methodology in SW Sicily in the surrounding of the area hit by the 1968 seismic sequence and in three other areas where evidence of active deformation has been recognized. Furthermore, to investigate the origin of emitted fluids, we measured the carbon isotopic composition of the soil CO2 in some high emission sites. The results showed high spatial variability of soil CO2 fluxes with values ranging from 1 to 430 g m−2d−1. The areal patterns of soil CO2 fluxes in all the areas reveal a strong influence of the main tectonic structures and active deformations on soil CO2 emissions. The range of isotopic data and the distribution of soil CO2 fluxes suggest a supply of deep fluids through the active tectonic structures.
    Description: Published
    Description: SE104
    Description: 2T. Deformazione crostale attiva
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: Soil CO2 flux ; Diffusive degassing structures (DDS) ; Active tectonic structures ; Belice Valley ; 04. Solid Earth ; 04.07. Tectonophysics
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  • 29
    Publication Date: 2020-09-21
    Description: The Italian Present-day Stress Indicators (IPSI) database is a freely available Italian georeferenced repository of information regarding the crustal stress field. It consists of horizontal stress orientations that have been analysed, compiled in a standardised format and quality-ranked for reliability and comparability on a global scale. The database contains a collection of information regarding contemporary stress within the shallow crust from the following main stress-indicator categories: borehole breakouts; earthquake focal mechanisms; seismic sequences and active fault-slip data. The present database (IPSI 1.4) released in January 2020 is accessible through a web interface which facilitates findability, accessibility, interoperability and reusability of the dataset. Moreover, it contains 928 records updated up until December 2019 with an increase of 10% with respect to the first one, and improved metadata information. The uniform spread of stress data over a given territory is relevant for earth crustal modelling or as starting point in many applied studies. It is therefore necessary to continue collecting new data and update present-day stress maps to obtain more reliable evaluations.
    Description: Published
    Description: id 298
    Description: 2T. Deformazione crostale attiva
    Description: 4IT. Banche dati
    Description: JCR Journal
    Keywords: present-day stress ; crustal stress ; borehole breakout ; earthquake focal mechanism ; active fault ; 04.07. Tectonophysics ; 04.04. Geology ; 04.06. Seismology
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  • 30
    Publication Date: 2020-09-07
    Description: While mantle convection is a fundamental ingredient of geodynamics, the driving mechanism of plate tectonics remains elusive. Are plates driven only from the thermal cooling of the mantle or are there further astronomical forces acting on them? GPS measurements are now accurate enough that, on long baselines, both secular plate motions and periodic tidal displacements are visible. The now 〉20 year-long space geodesy record of plate motions allows a more accurate analysis of the contribution of the horizontal component of the body tide in shifting the lithosphere. We review the data and show that lithospheric plates retain a non-zero horizontal component of the solid Earth tidal waves and their speed correlates with tidal harmonics. High-frequency semidiurnal Earth's tides are likely contributing to plate motions, but their residuals are still within the error of the present accuracy of GNSS data. The low-frequency body tides rather show horizontal residuals equal to the relative motion among plates, proving the astronomical input on plate dynamics. Plates move faster with nu- tation cyclicities of 8.8 and 18.6 years that correlate to lunar apsides migration and nodal precession. The high- frequency body tides are mostly buffered by the high viscosity of the lithosphere and the underlying mantle, whereas low-frequency horizontal tidal oscillations are compatible with the relaxation time of the low-velocity zone and can westerly drag the lithosphere over the asthenospheric mantle. Variable angular velocities among plates are controlled by the viscosity anisotropies in the decoupling layer within the low-velocity zone. Tidal oscillations also correlate with the seismic release.
    Description: Published
    Description: 103179
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Body tide ; Plate tectonics ; Geeodynamics ; 04.07. Tectonophysics
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  • 31
    Publication Date: 2020-10-16
    Description: High strain rates and intense seismic activity characterize both the boundaries and the interior of the Aegean–Anatolian plate: the availability of geodetic and geophysical data makes this region ideal to make detailed models of continental deformation. Although the deformation occurring in the Aegean–Anatolian plate may be regarded as the primary effect of the Arabian indenter push, it has already been demonstrated that this mechanism cannot account for the observed extrusion/rotation of the whole plate. We investigate the present-day steady-state anelastic deformation of the Aegean–Anatolian plate by a thin plate thermomechanical finite element (FE) model that accounts for realistic rheological mechanisms and lateral variations of lithospheric properties. Studying the region with uniform models, where average values for thermal and geometric parameters are chosen, we find that two tectonic features, in addition to the Arabian plate push, are critical to reproduce a velocity field that gives a reasonable fit to the observations. The first is the E–W constraint of NW continental Greece, related to the collision between the Aegean–Anatolian plate and the Apulia–Adriatic platform, required in the model to attain the SW orientation of the velocity field along the Hellenic Arc. The second is the trench suction force (TSF) due to subduction of the African lithosphere, which is needed to fit the observed mean extrusion velocity of 30 mm yr−1 along the Hellenic Arc. Uniform models are useful to study the sensitivity to the interplay of rheological/thermal parameters in a simplified framework but, in all cases, predict a strong deformation localized along the Hellenic Arc, whereas geodetic and seismological data show that the highest strain rates are located in western Anatolia. Furthermore, uniform models are non-unique in the sense that since we model a vertically averaged thin plate, different thermal and rheological parameters can be combined to yield the same lithospheric strength. We account for internal sources of deformation with heterogeneous models, where the available constraints on lateral variations of crustal thickness and surface heat flow have been included. The heterogeneous distribution of lithospheric strength contributes to ameliorate the fit to geodetic and stress data, since the predicted velocity field is characterized by an acceleration from E to W, with a sharp increase in the proximity of the western margin of the Anatolian peninsula, where the highest rates of intraplate deformation are observed. In our model this partitioning of the deformation is due to the different rheology of the Aegean Sea, which, being slightly deformable, transmits the TSF to the western margin of Anatolia. Our results are consistent with the interpretation of the Aegean–Anatolian system as a single, rheologically heterogeneous plate.
    Description: Published
    Description: 760-780
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Rheology ; Tectonics ; 04.07. Tectonophysics
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  • 32
    Publication Date: 2020-10-16
    Description: We revisit the problem of inferring mantle viscosity from postglacial relative sea level (RSL) data across the Hudson Bay. We invert a recently revised data set using the Metropolis algorithm together with an annealing schedule: this method, which is well established in geophysics, is applied here for the first time to the glacial isostatic adjustment problem. The Metropolis algorithm performs a search, which is not limited to downhill moves in the model space and thus is less influenced by local minima of the misfit than traditional inverse approaches. Furthermore, its CPU requirements are far superior to Monte Carlo methods. The major drawbacks include slow convergence and the need for careful tuning of crucial variables such as the temperature schedule and the increment in the model space. When all the Hudson Bay RSL data are considered, and the viscosity of the upper mantle above the 670 km discontinuity is inverted, the best fitting solution is characterized by a viscosity close to 2 × 10^20 Pa s. However, when the shallow upper mantle and transition zone viscosity are separately inverted, other less traditional solutions with a more complex viscosity structure are found to be equally possible. A stable feature is the lower mantle viscosity, which is generally found to be close to the value of 10^21 Pa s in all of the stochastic inversions we have performed. The solutions agree with previous findings concerning both postglacial rebound observables and global geodynamics signatures.
    Description: Published
    Description: 2352
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Postglacial Rebound ; Mantle Viscosity ; Simulated Annealing ; 04.07. Tectonophysics
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  • 33
    Publication Date: 2021-06-25
    Description: Recent measurements of surface vertical displacements of the European Alps show a correlation between vertical velocities and topographic features, with widespread uplift at rates of up to ~2–2.5 mm/a in the North-Western and Central Alps, and ~1 mm/a across a continuous region from the Eastern to the South-Western Alps. Such a rock uplift rate pattern is at odds with the horizontal velocity eld, characterized by shortening and crustal thickening in the Eastern Alps and very limited deformation in the Central and Western Alps. Proposed me- chanisms of rock uplift rate include isostatic response to the last deglaciation, long-term erosion, detachment of the Western Alpine slab, as well as lithospheric and surface de ection due to mantle convection. Here, we assess previous work and present new estimates of the contributions from these mechanisms. Given the large range of model estimates, the isostatic adjustment to deglaciation and erosion are su cient to explain the full observed rate of uplift in the Eastern Alps, which, if correct, would preclude a contribution from horizontal shortening and crustal thickening. Alternatively, uplift is a partitioned response to a range of mechanisms. In the Central and Western Alps, the lithospheric adjustment to deglaciation and erosion likely accounts for roughly half of the rock uplift rate, which points to a noticeable contribution by mantle-related processes such as detachment of the European slab and/or asthenospheric upwelling. While it is di cult to independently constrain the patterns and magnitude of mantle contributions to ongoing Alpine vertical displacements at present, future data should provide additional insights. Regardless, interacting tectonic and surface mass redistribution processes, rather than an individual forcing, best explain ongoing Alpine elevation changes.
    Description: Published
    Description: 589-604
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: 04. Solid Earth ; 04.03. Geodesy ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 34
    Publication Date: 2020-09-07
    Description: This study presents and discusses horizontal and vertical geodetic velocities for a low strain rate region of the south Alpine thrust front in northeastern Italy obtained by integrating GPS, interferometric synthetic aperture radar (InSAR) and leveling data. The area is characterized by the presence of subparallel, south-verging thrusts whose seismogenic potential is still poorly known. Horizontal GPS velocities show that this sector of the eastern Southern Alps is undergoing ∼1 mm a−1 of NW–SE shortening associated with the Adria–Eurasia plate convergence, but the horizontal GPS velocity gradient across the mountain front provides limited constraints on the geometry and slip rate of the several subparallel thrusts. In terms of vertical velocities, the three geodetic methods provide consistent results showing a positive velocity gradient, of ∼ 1.5 mm a−1, across the mountain front, which can hardly be explained solely by isostatic processes. We developed an interseismic dislocation model whose geometry is constrained by available subsurface geological reconstructions and instrumental seismicity. While a fraction of the measured uplift can be attributed to glacial and erosional isostatic processes, our results suggest that interseismic strain accumulation at the Montello and the Bassano–Valdobbiadene thrusts it significantly contributing to the measured uplift. The seismogenic potential of the Montello thrust turns out to be smaller than that of the Bassano–Valdobbiadene fault, whose estimated parameters (locking depth equals 9.1 km and slip rate equals 2.1 mm a−1) indicate a structure capable of potentially generating a Mw〉6.5 earthquake. These results demonstrate the importance of precise vertical ground velocity data for modeling interseismic strain accumulation in slowly deforming regions where seismological and geomorphological evidence of active tectonics is often scarce or not conclusive.
    Description: Published
    Description: 1681–1698
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Southern Alps ; Vertical Velocities ; GPS and InSAR integration ; Interseismic Deformation ; Dislocation Model ; Seismic Potential ; 04.03. Geodesy ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 35
    Publication Date: 2020-10-16
    Description: Recent satellite geodetic measurements help to clearly define the velocity field in the Aegean-Anatolian area. The velocity field can be broadly characterized by anticlockwise rotation of this region relative to Eurasia, around a pole located at Lat. 32.73, Long. 32.03, north of the Egyptian shoreline. Studies of the fault kinematics in the region also provide information on the time evolution of the stress field. In this work, we model deformation in the Aegean-Anatolian region to better understand the tectonic origin of the observed stress and velocity fields. We found that the observed deformation pattern can be well reproduced by imposing simple boundary conditions including: (1) northward displacement of the Arabian plate, (2) locking of eastward motion in northwestern Greece and (3) suction force at the Hellenic trench. The observed variation in the stress field occurred at 0.9 Ma can be partially explained by a change in the activity of the North Anatolian fault.
    Description: Published
    Description: 2087-2090
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Plate Motion ; Continental tectonics ; Dynamics of lithosphere and mantle ; Plate boundary ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 36
    Publication Date: 2021-01-27
    Description: Il progetto SPOT (Sismicità Potenzialmente innescabile Offshore e Tsunami) è stato sviluppato con lo scopo di supportare le Autorità italiane nell'applicazione della Direttiva Europea sulla sicurezza delle operazioni in mare nel settore degli idrocarburi (2013/30/EU), su fondi di cui art. 35 del Decreto Legge 83/2012, e dei decreti italiani che ne derivano (Antoncecchi et al., 2019). Il progetto, della durata di 21 mesi, è stato ideato e finanziato dal Ministero dello Sviluppo Economico italiano – Direzione Generale per la sicurezza delle attività minerarie ed energetiche (DGS-UNMIG) nell’ambito della rete di ricerca CLYPEA, con il supporto tecnico del Dipartimento della Protezione Civile nazionale.
    Description: Attività svolta nell'ambito del programma CLYPEA - Innovation Network for Future Energy, finanziato dal Ministero dello Sviluppo Economico su fondi per la "sicurezza offshore" ai sensi dell'art.35 D.L. 83/2012.
    Description: Published
    Description: 2T. Deformazione crostale attiva
    Description: 4T. Sismicità dell'Italia
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: 4IT. Banche dati
    Keywords: Italia ; Mare Adriatico ; Mare Ionio ; Canale di Sicilia ; terremoto ; maremoto ; tsunami ; sismicità offshore ; frana sottomarina ; vulnerabilità del costruito ; scenario di impatto ; rischio sismico ; rischio tsunami ; sicurezza marina ; produzione idrocarburi ; 04.07. Tectonophysics ; 04.02. Exploration geophysics ; 05.08. Risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 37
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    Research Open (https://researchopenworld.com/category/geology-earth-marine-sciences/)
    Publication Date: 2020-01-20
    Description: The geodynamic evolution of central Chile-Argentina is mainly controlled by the subduction of the oceanic Nazca plate beneath the continental South American lithosphere. In particular, between 29°S and 34°S, the Nazca plate exhibits a flat-slab subduction around 100 km of depth, that extends eastward for hundreds of km before returning to a downward descent. This condition causes an interruption in the Andean volcanic arc and an intense crustal deformation that continues toward the craton, beyond the foreland thrust belt. The outcome is a very active crustal seismicity and complicated structural framework. In order to study the seismotectonic characteristics of this flat-slab region, we analyzed data recorded by a local network, performing a simultaneous inversion of both the velocity structure and the hypocentre parameters. The availability of accurate hypocentre locations and finely tuned velocity distribution allows us to improve the earthquake source characterization and the knowledge on the ongoing seismotectonics of the region.
    Description: Published
    Description: 1-4
    Description: 1T. Struttura della Terra
    Description: N/A or not JCR
    Keywords: central Andes ; seismic tomography ; Flat-slab subduction ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
    Publication Date: 2020-02-20
    Description: Istituto Nazionale di Geofisica e vulcanologia
    Description: Published
    Description: 2T. Deformazione crostale attiva
    Keywords: present-day stress ; borehole breakout ; earthquake focal mechanism ; 04.07. Tectonophysics ; 04.06. Seismology ; 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: web product
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  • 39
    Publication Date: 2020-03-03
    Description: This article has been accepted for publication in Geophysical Journal International ©: 2014, Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
    Description: In this work, we present a study of the coseismic and post-seismic crustal deformation associ- ated to the Mw 6.3, 2009 April 6 L’Aquila earthquake from the analysis of GPS displacement time-series. We use a principal component decomposition-based inversion method to study the space- and time-dependent evolution of slip on faults without any a priori assumption on the model used to characterize the temporal evolution of crustal deformation. The method adopted allows us to account for the initial post-seismic deformation in estimating the coseismic dis- placements, in a consistent manner for the whole GPS network. We use elastic dislocation theory and a least-squares procedure to invert for the slip distribution on the mainshock fault (Paganica fault) and a second fault (Campotosto fault), where a Mw 5.2 aftershock occurred on April 9. The geometries for these faults are obtained from a singular value decomposition of precisely relocated aftershocks. We find that the use of complex fault geometries is not justified by the GPS observations available. An inversion that accounts for post-seismic slip to occur on both the Paganica and Campotosto faults provides a better fit to the GPS time-series observations, than using only the Paganica fault segment, at a 95 per cent confidence level. Within our resolution, afterslip regions do not migrate over time and are localized on fault patches that are approximately complementary to those of coseismic slip. We find that the position of some relevant afterslip patches is different if the inversion is performed assuming a fixed rake or not. We estimate the parameter a – b of rate- and state-dependent friction on those fault regions accommodating afterslip that are robustly characterized in our inversions. We find values of the order of 10−3, which is near the transition from potentially unstable to nominally stable friction. These results are in agreement with laboratory measurements performed on typical rocks of the L’Aquila region.
    Description: Published
    Description: 174–191
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: 3T. Sorgente sismica
    Description: JCR Journal
    Keywords: 04. Solid Earth ; 04.03. Geodesy ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
    Publication Date: 2020-06-10
    Description: Understanding how long-term subduction dynamics relates to the short-term seismicity and crustal tec tonics is a challenging but crucial topic in seismotectonics. We attempt to address this issue by linking long-term geodynamic evolution with short-term seismogenic deformation in the Northern Apennines. This retreating subduction orogen displays tectonic and seismogenic behaviors on various spatiotemporal scales that also characterize other subduction zones in the Mediterranean area. We use visco-elasto-plastic seismo-thermo-mechanical (STM) modeling with a realistic 2D setup based on available geological and geophysical data. The subduction dynamics and seismicity are coupled in the numerical modeling, and driven only by buoyancy forces, i.e., slab pull. Our results suggest that lower crustal rheology and lithospheric mantle temperature modulate the crustal tectonics of the Northern Apennines, as inferred by previous studies. The observed spatial distribution of upper crustal tectonic regimes and surface displacements requires buoyant, highly ductile material in the subduction channel beneath the internal part of the orogen. This allows protrusion of the asthenosphere in the lower crust and lithospheric delamination associated with slab retreat. The resulting surface velocities and principal stress axes generally agree with present-day observations, suggesting that slab delamination and retreat can explain the dynamics of the orogen. Our simulations successfully reproduce the type and overall distribution of seismicity with thrust faulting events in the external part of the orogen and normal faulting in its internal part. Slab temperatures and lithospheric mantle stiffness affect the cumulative seismic moment release and spatial distribution of upper crustal earthquakes. The properties of deep, sub-crustal material are thus shown to influence upper crustal seismicity in an orogen driven by slab retreat, even though the upper crust is largely decoupled from the lithospheric mantle. Our simulations therefore highlight the effect of deep lower crustal rheologies, self-driven subduction dynamics and mantle properties in controlling shallow deformation and seismicity.
    Description: Published
    Description: 228481
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Numerical modeling ; Geodynamics ; Seismotectonics orogen ; Delamination ; Northern Apennines ; 04.06. Seismology ; 04.03. Geodesy ; 05.01. Computational geophysics ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
    Publication Date: 2020-02-07
    Description: The Valle Umbra is a NW-SE 20 km long and 10 km wide Quaternary alluvial basin located in the internal sector of the active extensional tectonic Apennine chain, central Italy. This area historically suffered major earthquakes such as in 1832 (ME=6.3; I0=X) and 1854 (Me=5.6; I=VIII), both localized in the valley. It was marginally affected by the seismic event localized in the Colfiorito basin (M 6.0; September 1997) and more recently suffered from damages to buildings caused by the last seismic sequence of Amatrice-Visso-Norcia (main shock, Norcia, PG, Mw 6.5, 30 October 2016). We investigate the presence of active segments that may be hidden under the unconsolidated deposits filling the basin. We integrate single station ambient noise measurements with previously acquired seismic reflection data and surface geology in order to reconstruct the subsurface geometry of the basin and localize buried faults. Preliminary results from the ambient noise spectral ratios show, in general, one resonance peak at around 0.8 - 1 Hz for stations installed on the lower Pleistocene deposits overlapping the Miocenic bedrock and two resonance peaks for stations installed in the alluvial infill deposits in the central portion of the valley. An accelerometric station of the national civil protection provided us additional constraints about the level of amplification of the site, (connected to the presence of impedance contrasts in the subsoil) as recovered by spectral ratio analysis of several earthquakes recorded from the 1986 up to date. Moreover, the availability of more than 20 years of SAR data archives for the studied area, allowed us the observation of a differential ground subsidence, detected by means of the application of Differential InSAR techniques. The subsidence can be due to either human induced aquifers withdrawal or to tectonic of the area, and we interpret that these can be co-responsible for the observed subsidence pattern. Through the correlation of the time-series of observed recent ground deformations with the buried geological structures identified using geophysical techniques, we made an attempt of detecting and characterizing the geologic heterogeneities in the subsurface, defining the geometry and kinematics of the buried faults and eventually addressing the seismogenic potential of the area.
    Description: Unpublished
    Description: La Valletta (Malta)
    Description: 3T. Sorgente sismica
    Keywords: Seismic noise ; Valle Umbra ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 42
    Publication Date: 2020-05-19
    Description: The dynamics of continental subduction is largely controlled by the rheological properties of rocks involved along the subduction channel. Serpentinites have low viscosity at geological strain rates. However, compelling geophysical evidence of a serpentinite channel during continental subduction is still lacking. Here we show that anomalously low shear-wave seismic velocities are found beneath the Western Alps, along the plate interface between the European slab and the overlying Adriatic mantle. We propose that these seismic velocities indicate the stacked remnants of a weak fossilised serpentinite channel, which includes both slivers of abyssal serpentinite formed at the ocean floor and mantle-wedge serpentinite formed by fluid release from the subducting slab. Our results suggest that this serpentinized plate interface may have favoured the subduction of continental crust into the upper mantle and the formation/exhumation of ultra-high pressure metamorphic rocks, providing new constraints to develop the conceptual and quantitative understanding of continental-subduction dynamics.
    Description: This research was supported by NSFC (grant nos. 41888101, 91755000, and 41625016), CAS program (GJHZ1776), Agence Nationale de la Recherche (contract ANR-15-CE31-0015), and Labex OSUG@2020 (Investissement d’Avenir, ANR-10-LABX-56). T.B. is funded by the European Union’s Horizon 2020 research and innovation program (grant no. 716542). This is contribution 1484 from the ARC Centre of Excellence for Core to Crust Fluid Systems (http://www.ccfs.mq.edu.au). This work was supported by resources provided by the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia.
    Description: Published
    Description: id 2171
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Lithosphere reology ; serpentinites ; subduction ; Western Alps ; exhumation ; 04.01. Earth Interior ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 43
    Publication Date: 2020-07-13
    Description: A multidisciplinary field campaign was carried out at Nisyros Island (Greece). Hydrothermal gases were sampled and analysed, and CH4 and CO2 fluxes from the soils were measured with the accumulation chamber method. The sampling area (Lakki plain) covers an area of about 0.08 km2, and includes the main fumarolic areas of Kaminakia, Stefanos, Ramos, Lofos and Phlegeton. Flux values measured at 130 sites range from −3.4 to 1420 mg m−2 d−1 for CH4 and from 0.1 to 383 g m−2 d−1 for CO2. The fumarolic areas show very different CH4 degassing patterns, Kaminakia showing the highest CH4 output values (about 0.8 t a−1 from an area of about 30,000 m2) and Phlegeton the lowest (about 0.01 t a−1 from an area of about 2500 m2). The total output from the entire geothermal system of Nisyros should not exceed 2 t a−1. Previous indirect estimates of the CH4 output at Nisyros, based on soil CO2 output and CH4/CO2 ratios in fumarolic gases, were more than one order of magnitude higher. The present work further underscores the utmost importance of direct CH4 flux data because indirect methods totally disregard methanotrophic activity within the soil. Ten soil samples were collected for CH4 consumption experiments and for metagenomic analysis. Seven of the soil samples showed small but significant CH4 consumption (up to 39.7 ng g−1 h−1) and were positive for the methanotrophs-specific gene (pmoA) confirming microbial CH4 oxidation in the soil, notwithstanding the harsh environmental conditions (high temperature and H2S concentrations and low pH).
    Description: Published
    Description: 119546
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: Methanotrophy ; Soil degassing ; Hydrothermal systems ; Methane output ; Greenhouse gases ; 05.09. Miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 44
    Publication Date: 2020-06-30
    Description: Quantification of the CO2 released by the volcanoes to the atmosphere is relevant for the evaluation of the balance between deep-derived, biogenic and anthropogenic contributions. The current study estimates the CO2 released from Furnas do Enxofre degassing area (Terceira Island, Azores archipelago) by applying an approach that integrates the flux of CO2 fromthe soilwith the δ13C-CO2 values. A deep-derived CO2 output of 2.54 t d−1 is estimated for an area of ~23,715 m2. High biogenic-derived CO2 flux values (~45 g m−2 d−1) associated with light carbon isotopic content (δ13C=−28‰±1.1‰) are detected and explained by the type of vegetation that characterizes the study site. Carbon isotopic compositions of the CO2 (−6.4‰±1.2‰) measured in olivine-hosted fluid inclusions of the Terceira basalts are presented for the first time and contribute to defining the mantle-CO2 signature. Differences between these values and heavier carbon isotope values from gas in fumaroles at Furnas do Enxofre (−4.66‰to−4.27‰) are explained by the carbon isotopic fractionation occurring when CO2 reacts to form calcite in the geothermal reservoir at temperatures N180 °C. A clear correlation between the soil temperature and deep CO2 fluxes is observed and the integration of the diffuse degassing information with the composition of the fumarolic emissions allows estimating a thermal energy flux of 1.1 MW.
    Description: Published
    Description: 106968
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: Soil diffuse degassing ; CO2 fluxes ; Carbon isotopic composition ; Hydrothermal systems ; 04.08. Volcanology ; 04.01. Earth Interior
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 45
    Publication Date: 2020-07-08
    Description: The response of continental forelands to subduction and collision is a widely investigated topic in geodynamics. The deformation occurring within a foreland shared by two opposite‐verging chains, however, is uncommon and poorly understood. The Apulia Swell in the southern end of the Adria microplate (Africa‐Europe plate boundary, central Mediterranean Sea) represents one of these cases, as it is the common foreland of the SW verging Albanides‐Hellenides and the NE verging Southern Apennines merging into the SSE verging Calabrian Arc. We investigated the internal deformation of the Apulia Swell using multiscale geophysical data: multichannel seismic profiles recording up to 12‐s two‐way time (TWT) for a consistent image of the upper crust; high‐resolution multichannel seismic profiles, high‐resolution multibeam bathymetry, and CHIRP profiles acquired by R/V OGS Explora to constrain the Quaternary geological record. The results of our analyses characterize the geometry of the South Apulia Fault System (SAFS), a 100‐km‐long and 12‐km‐wide structure attesting an extensional (and possibly transtensional) response of the foreland to the two contractional fronts. The SAFS consists of two NW‐SE right‐stepping master faults and several secondary structures. The SAFS activity spans from the Early Pleistocene through the Holocene, as testified by the bathymetric and high‐resolution seismic data, with long‐term slip rates in the range of 0.2–0.4 mm/yr. Considering the position within an area with few or none other active faults in the surroundings, the dimension, and the activity rates, the SAFS can be a candidate causative fault of the 20 February 1743, M 6.7, earthquake.
    Description: Italian Ministry for Education, University, and Research (MIUR), Premiale 2014 D. M. 291 03/05/2016.
    Description: Published
    Description: e2020TC006116
    Description: 2T. Deformazione crostale attiva
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Keywords: active tectonics ; apulia ; south apulia fault system ; 1743 earthquake ; marine geology ; stable continental region ; ionian sea ; active faults ; subsurface geology ; seismic interpretation ; 04.04. Geology ; 04.07. Tectonophysics ; 04.02. Exploration geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
    Publication Date: 2020-05-21
    Description: Fluid primary source(s) and chemical-physical processes controlling water and gas chemistry of thermal springs from Eastern Cordillera, sub-Andean Ranges and Santa Bárbara (Jujuy Province, northern Argentina) were investigated to provide information for a preliminary evaluation of the geothermal potential in these areas. Thermal manifestations in Eastern Cordillera (Reyes) and part of those in the western sector of sub-Andean Range (Aguas Calientes) are fed by shallow aquifers, interacting with Quaternary- Neogene rocks and the upper portion of Pliocene-Miocene formations (Orán Group), whereas the meteoric water recharge area is located at〉2500 m a.s.l., corresponding to Chañi hill. Differently, El Jordán thermal spring in the sub-Andean Range is fed by a hydrothermal aquifer hosted within highly porous and fractured formations of the Salta Group (Yacoraite Formation) and recharged by meteoric water from Sierra de Calilegua (∼1500m a.s.l.). The latter is the recharge area of the La Quinta geothermal waters as well, but these have been fed at higher altitudes (〉 2500 m a.s.l.) in the range. The hydrothermal reservoir feeding the other thermal springs from the Santa Barbara system (Caimancito, El Palmar, and Siete Aguas) is recharged by meteoric water from Zapla Ranges and Santa Barbara Hill at〈2500m a.s.l. The high-TDS (〉 16,000 mg/L) Na+-Cl- La Quinta thermal springs are produced by interaction with the evaporite deposits of Salta Group, including halite, whereas the chemistry of El Palmar, El Jordán and Caimancito thermal springs, showing a Na+-SO4 2-(Cl−) composition, depends on mixing with shallower SO4 2--rich waters interacting with gypsum deposits of Anta Formation. Dissolved and bubbling gases from all the investigated provinces are related to CO2- and CH4-rich crustal fluids produced by both thermogenic processes occurring within the hydrothermal systems and microbial activity at relatively low depth, with low to negligible mantle contribution, as indicated by the 3He/4He values ≤ 0.21 Ra. The fluid reservoir feeding the Quinta thermal springs shows the highest estimated temperatures (〉 200 °C), which, considering the depth of Salta Group in the Santa Barbara system (~2000 m), support the idea, suggested by previous authors, of an anomalous geothermal gradient for this area, a promising pre-requisite for future exploitation of the geothermal resource.
    Description: Published
    Description: 102627
    Description: 1TR. Georisorse
    Description: JCR Journal
    Keywords: Hydrothermal systems ; Fluid geochemistry ; Jujuy province ; Geothermal resource
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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