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  • 04.07. Tectonophysics  (7)
  • Elsevier  (7)
  • American Association for the Advancement of Science
  • 2020-2023  (7)
  • 1985-1989
  • 1980-1984
  • 1925-1929
  • 1
    Publication Date: 2022-04-01
    Description: The Gutenberg–Richter law and the Omori law are both characterized by a scaling behavior. However, their relation is still an open question. Although several hypotheses have been formulated, a comprehen- sive geophysical mechanism is still missing to explain the observed variability of the scaling exponents b-value and p-value, e.g., correlating the seismic cycle to statistical seismology and tectonic processes. In this work, a model for describing the size-frequency scaling and the temporal evolution of seismicity is proposed starting from simple assumptions. The parameter describing how the number of earthquakes decreases after a major seismic event, p, turns out to be positively correlated to the exponent of the frequency-size distribution of seismicity, b, and related to tectonics. Our findings suggest that p ≈ 23 (b + 1). It implies that a relationship between fracturing regimes, “efficiency” of the seismic process, duration of the seismic sequences and geodynamic setting exists, with outstanding potential impact on seismic hazard. On the other hand, the Gutenberg–Richter law simply reflects the tendency of the segments of the Earth’s crust to reach mechanical stability via constrained energy-budget optimization. Each perturbation has a probability of growing an earthquake or not, depending on disorder within the fault zone and the energy accumulated in the adjoining volume, mainly controlling the evolution of seismic sequences. The results are consistent with the different energy sources related to the tectonic settings, i.e., gravitational in extensional regimes, having higher b and p values, and generating lower maximum magnitude earthquakes with respect to strike-slip and contractional settings, which are rather fueled by elastic energy, showing lower b and p values, and they may generate higher magnitude events.
    Description: Published
    Description: 117511
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: Gutenberg–Richter distribution ; fracturing and fault disorder ; Omori–Utsu law ; earthquake triggering ; tectonic setting ; 04.06. Seismology ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2022-04-29
    Description: We carried out new geological, morphotectonic, geophysical and paleoseismological investigations on the Meduno Thrust that belongs to the Pliocene-Quaternary front of the eastern Southern Alps in Friuli (NE Italy). The study area is located in the Carnic Prealps, where a series of alluvial terraces, linked to both climatic and tectonic pulses characterises the lower reach of the Meduna Valley. In correspondence of the oblique ramp of the Meduno Thrust, the Late Pleistocene Rivalunga terrace shows a set of scarps perpendicular to the Meduno valley, often modified by human activity. In order to reconstruct the tectonic setting of the area and identify the location for digging paleoseismological trenches, integrated geophysical investigations including electrical resistivity tomography, seismic refraction and reflection, ground penetrating radar and surface wave analyses (HVSR, ReMi and MASW), were carried out across the scarps of the Rivalunga terrace. Geophysical surveys pinpointed that in correspondence of the oblique ramp, stress is accommodated by a transpressive thrust system involving all the seismo-stratigraphic horizons apart from the ploughed soil. Trenching illustrated the Meduno Thrust movements during Late Pleistocene-Holocene. Trenches exhibited both shear planes and extrados fracturing, showing deformed alluvial and colluvial units. 14C datings of the colluvial units show that the most recent fault movements occurred after 1360 CE and 1670 CE. The age of the deformed stratigraphic units compared with the earthquakes listed in current catalogues, suggests that the 1776 earthquake (Mw 5.8, Io = 8–9 MCS) could represent the last seismic event linked to the Meduno thrust activity. This study provided new quantitative constraints improving seismic hazard assessment for Carnic prealpine area.
    Description: The research developed in the framework of the agreement between the Regione Autonoma Friuli Venezia Giulia - Direzione Centrale Ambiente ed Energia - Servizio Geologico, the Istituto Superiore per la Protezione e la Ricerca Ambientale (I.S.P.R.A.) and the University of Udine. The project was funded by the Regione Autonoma Friuli Venezia Giulia, Direzione Centrale Ambiente ed Energia, Servizio Geologico (C.I. G.: Z0E0C5EF75, p.i. Maria Eliana Poli).
    Description: Published
    Description: 229071
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Active fault ; Paleoseismology ; Morphogenic earthquake ; Eastern Southern Alps ; Applied geophysics ; NE Italy ; 04.04. Geology ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Elsevier
    Publication Date: 2022-02-10
    Description: The airborne magnetic method was established a few decades ago, as a strong tool in mining and petroleum exploration. Several economically relevant discoveries are often credited to aeromagnetism. Geological reconnaissance and mapping, deep crustal and upper mantle studies, environmental characterization, and national and international security issues can greatly benefit from the aeromagnetic method, as compared with other geophysical prospecting schemes. The rapid rate of coverage and the low cost per unit area explored represent just a few among the many advantages of the technique. Consequently, large-scale airborne magnetic surveys have been carried out in various parts of the globe. The amount of direct discoveries of ore bodies by means of aeromagnetism is impressive. Large magnetic iron deposits found in the early 1960s are in Southern California, Missouri, Nevada, Pennsylvania, Quebec, Ontario, and elsewhere. In the field of petroleum exploration, the method has also been used, although with less direct application. Depth to magnetic basement estimation in sedimentary basins narrows down areas of interest where to conduct exploration surveys in detail by means of more costly methods. The most relevant use of airborne magnetic results is crustal imaging and characterization. Nowadays, geology is interpreted in three dimensions using a digital aeromagnetic map.
    Description: Published
    Description: 675-688
    Description: 1T. Struttura della Terra
    Description: 4T. Sismicità dell'Italia
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: 1V. Storia eruttiva
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 3A. Geofisica marina e osservazioni multiparametriche a fondo mare
    Description: 5A. Ricerche polari e paleoclima
    Description: 7A. Geofisica per il monitoraggio ambientale
    Description: 1TR. Georisorse
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: 6SR VULCANI – Servizi e ricerca per la società
    Description: 7SR AMBIENTE – Servizi e ricerca per la società
    Keywords: aeromagnetism ; potential fields ; magnetic anomaly ; 04.02. Exploration geophysics ; 04.05. Geomagnetism ; 04.07. Tectonophysics ; 04.08. Volcanology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 4
    Publication Date: 2022-02-22
    Description: The westernmost Mediterranean hosts part of the plate boundary between the European and African tectonic plates. Based on the scattered instrumental seismicity, this boundary has been traditionally interpreted as a wide zone of diffuse deformation. However, recent seismic images and seafloor mapping studies support that most of the plate convergence may be accommodated in a few tectonic structures, rather than in a broad region. Historical earthquakes with magnitudes Mw 〉 6 and historical tsunamis support that the low-to-moderate instrumental seismicity might also have led to underestimation of the seismogenic and tsunamigenic potential of the area. We evaluate the largest active faults of the westernmost Mediterranean: the reverse Alboran Ridge, and the strike-slip Carboneras, Yusuf and Al-Idrissi fault systems. For the first time, we use a dense grid of modern seismic data to characterize the entire dimensions of the main fault systems, accurately describe the geometry of these structures and estimate their seismic source parameters. Tsunami scenarios have been tested based on 3D-surfaces and seismic source parameters, using both uniform and heterogeneous slip distributions. The comparison of our results with previous studies, based on limited information on the fault geometry and kinematics, indicates that accurate fault geometries and heterogeneous slip distributions are needed to properly assess the seismic and tsunamigenic potential in this area. Based on fault scaling relations, the four fault systems have a large seismogenic potential, being able to generate earthquakes with Mw 〉 7. The reverse Alboran Ridge Fault System has the largest tsunamigenic potential, being able to generate a tsunami wave amplitude greater than 3 m in front of the coasts of Southern Spain and Northern Africa.
    Description: Published
    Description: 106749
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: Western Mediterranean ; Seismogenic potential ; Tsunamigenic potential ; Numerical modelling ; Active faults ; Active seismic data ; 04.04. Geology ; 04.07. Tectonophysics ; 04.06. Seismology ; 05.08. Risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2022-09-15
    Description: We have mapped and constrained the timing of tectonically deformed uplifted Late Quaternary palaeoshorelines in the Messina Strait, southern Italy, an area above a subduction zone containing active normal faults. The palaeoshorelines are preserved from up to thirteen Late Quaternary sea-level highstands, providing a record of the deformation over this timescale (~500 ka) for the Messina-Taormina Fault, the Reggio Calabria Fault and the Armo Fault. The palaeoshorelines reveal spatial patterns of uplift through time along the strike of these normal faults, and, given the across strike arrangement of the faults, also reveal how the contribution of each fault to the regional strain-rate progressed through time. The results reveal that the uplift rates mapped within the fault hangingwalls and footwalls were not constant through time, with a marked change in the location of strain accumulation at ~50 ka. The uplift rates, once converted into throw-rates, imply that the three faults comprised similar throw-rates prior to ~50 ka (in the range 0.77–0.96 mm/yr), with the Armo and Reggio Calabria faults then switching to lower rates (0.32 mm/yr and 0.33 mm/yr respectively), whilst the Messina-Taormina Fault accelerated to 2.34 mm/yr. The regional extension rate, gained by summing the implied heave rates across the three faults, was maintained through time despite this re-organisation of local strain accumulation at ~50 ka. We explain these out-of-phase fault throw-rate changes during the constant-rate regional extension conditions as due to interactions between these upper plate normal faults. We finally discuss how fault throw-rates changing through time may affect a long-term seismic hazard assessment within active normal fault systems.
    Description: Published
    Description: 105432
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Crustal Deformation ; Active Faults ; Marine terraces ; Uplift ; 04.04. Geology ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2022-06-09
    Description: Joint analysis of high-penetration multi-channel and high-resolution single-channel seismic reflection profiles, calibrated by deep well boreholes, allowed a detailed reconstruction of the Late Miocene to Recent tectonic history of the Capo Granitola and Sciacca fault systems offshore southwestern Sicily. These two fault arrays are part of a regional system of transcurrent faults that dissect the foreland block in front of the Neogene Sicilian fold and thrust belt. The Capo Granitola and Sciacca faults are thought to reactivate inherited Mesozoic to Miocene normal faults developed on the northern continental margin of Africa. During Latest Miocene-Pliocene, the two ~NNE-SSW striking faults were active in left transpression, which inverted Late Miocene extensional half-grabens and created push-up ridges along both systems. Tectonic activity decreased during the Pleistocene, but transpressional folds deform Middle-Late Pleistocene sediments as well, suggesting that the two fault systems are active. The ~40 km long longitudinal amplitude profile of 1st order folds (Capo Granitola and Sciacca anticlines) shows ~15–20 km bell-shaped undulations that represents 2nd order folds. The length of these undulations together with the map pattern of faults allowed to divide the CGFS and SFS into two segments, northern and southern, respectively. Total uplift of the Sciacca Anticline is twice than the uplift of the Capo Granitola Anticline. Incremental fold growth rates decreased during time from 0.22 mm/yr (Capo Granitola Anticline) and 0.44 mm/yr (Sciacca Anticline) in the Pliocene, to 0.07 and 0.22 mm/yr, respectively, during the last ~1.8 Ma.
    Description: Published
    Description: 187-204
    Description: 2T. Deformazione crostale attiva
    Description: 3A. Geofisica marina e osservazioni multiparametriche a fondo mare
    Description: JCR Journal
    Keywords: Multiscale analysis ; Basin inversion ; Strike-slip faults ; Fold growth rates ; Pelagian foreland ; SW Sicily offshore ; 04.07. Tectonophysics ; 04.04. Geology ; 04.02. Exploration geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2022-06-09
    Description: Young and tectonically active chains like the Central Apennines (Italy) are featured by high structural complexity as a result of the overprint of subsequent deformational stages, making interpretation of seismotectonics challenging. The Central Apennines are characterized by the stacking of tectono-sedimentary units organized in thrust sheets. However, extensional tectonics is currently affecting the axial sector of the thrust belt, mostly expressing in extensional earthquakes. Using a large subsurface dataset acquired for hydrocarbon exploration in the region struck by the 2016–2017 Central Italy seismic sequence, we built a comprehensive 3D geological model and compared it with the seismicity. The model primarily shows a series of thrusts developed during the Miocene-Pliocene Apennines orogenesis and inherited normal faults developed during the Mesozoic extensional phase and the Miocene foreland flexural process. These normal faults were segmented and transported within the thrust sheets, and sometimes they still show a clear surface expression. The succession of tectonic stages resulted in a widespread reactivation of inherited structures, sometimes inverting their kinematics with different styles and rates, and disarticulating pre-existing configurations. Such evolution has a strong impact on the seismicity observed in the area, as demonstrated by some examples that show how the seismicity is aligned on segments of inherited faults, both compressional and extensional. Their reactivation can be explained by their favorable orientation within the current extensional stress field. Results feed the debate about the seismogenic potential of faults identified both at depth and surface, which can impact the seismic hazard of the Apennines.
    Description: Published
    Description: 228861
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: Normal faults ; Thrust sheets ; Inherited faults ; Earthquakes ; Central Apennines ; 3D geological model ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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