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  • Articles  (9)
  • 04.07. Tectonophysics  (6)
  • Multi-GAS  (3)
  • Elsevier  (7)
  • EGU - Copernicus  (2)
  • 2020-2022  (9)
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  • 1950-1954
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  • 1
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    The epicentral fingerprint of earthquakes marks the coseismically activated crustal volume (2021)
    Elsevier
    Details
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Asymmetric Atlantic continental margins (2021)
    Elsevier
    Details
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Geodynamic and seismotectonic model of a long-lived transverse structure: The Schio-Vicenza Fault System (NE Italy) (2021)
    EGU - Copernicus
    Details
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Characterisation of the magmatic signature in gas emissions from Turrialba Volcano, Costa Rica (2020)
    EGU - Copernicus
    Details
    Publication Date: 2020-11-25
    Description: The equilibrium composition of volcanic gaseswith their magma is often overprinted by interaction with ashallow hydrothermal system. Identifying the magmatic sig-nature of volcanic gases is critical to relate their composi-tion to properties of the magma (temperature,fO2, gas-meltsegregation depth). We report measurements of the chemi-cal composition and flux of the major gas species emittedfrom Turrialba Volcano during March 2013. Measurementswere made of two vents in the summit region, one of whichopened in 2010 and the other in 2012. We determined an av-erage SO2flux of 5.2±1.9 kg s−1using scanning ultravio-let spectroscopy, and molar proportions of H2O, CO2, SO2,HCl, CO and H2gases of 94.16, 4.03, 1.56, 0.23, 0.003 and0.009 % respectively by open-path Fourier transform infrared(FTIR) spectrometry and a multi-species gas-sensing system.Together, these data imply fluxes of 88, 8, 0.44, 5×10−3and1×10−3kg s−1for H2O, CO2, HCl, CO and H2respectively.Although H2S was detected, its concentration could not beresolved. HF was not detected. The chemical signature of thegas from both vents was found to be broadly similar. Follow-ing the opening of the 2010 and 2012 vents we found limitedto negligible interaction of the magmatic gas with the hy-drothermal system has occurred and the gas composition ofthe volcanic plume is broadly representative of equilibriumwith the magma. The time evolution of the gas composition,the continuous emission of large quantities of SO2, and thephysical evolution of the summit area with new vent open-ings and more frequent eruptions all point towards a continu-ous drying of the hydrothermal system at Turrialba’s summitat an apparently increasing rate.
    Description: This research was supported by the RoyalGeographical Society (with IBG) with a Geographical FieldworkGrant. Y. Moussallam and N. Peters were additionally supportedby the Philip Lake funds from the Department of Geography,University of Cambridge. Y. Moussallam acknowledges a researchgrant from Mazamas and support through ERC project #279790.We thank the NERC Field Spectroscopy Facility for the loanof their infrared spectrometer. A. Aiuppa acknowledges supportthrough ERC grant no. 305377 (BRIDGE)
    Description: Published
    Description: 1341–1350
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: volcanic degassing ; Multi-GAS ; UV spectroscopy ; FTIR ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Tidal modulation of plate motions (2020)
    Elsevier
    Details
    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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Sustaining persistent lava lakes: Observations from high-resolution gas measurements at Villarrica volcano, Chile (2020)
    Elsevier
    Details
    Publication Date: 2020-11-25
    Description: Active lava lakes – as the exposed upper part of magmatic columns – are prime locations to investigate the conduit flow processes operating at active, degassing volcanoes. Persistent lava lakes require a constant influx of heat to sustain a molten state at the Earth's surface. Several mechanisms have been proposed to explain how such heat transfer can operate efficiently. These models make contrasting predictions with respect to the flow dynamics in volcanic conduits and should result in dissimilar volatile emissions at the surface. Here we look at high-frequency SO2 fluxes, plume composition, thermal emissions and aerial video footage from the Villarrica lava lake in order to determine the mechanism sustaining its activity. We found that while fluctuations are apparent in all datasets, none shows a stable periodic behaviour. These observations suggest a continuous influx of volatiles and magma to the Villarrica lava lake. We suggest that ascending volatile-rich and descending degassed magmas are efficiently mixed within the volcanic conduit, resulting in no clear periodic oscillations in the plume composition and flux. We compare our findings to those of other lava lakes where equivalent gas emission time-series have been acquired, and suggest that gas flux, magma viscosity and conduit geometry are key parameters determining which flow mechanism operates in a given volcanic conduit. The range of conduit flow regimes inferred from the few studied lava lakes gives a glimpse of the potentially wide spectrum of conduit flow dynamics operating at active volcanoes.
    Description: This research was conducted as part of the “Trail By Fire” expedition (PI: Y. Moussallam). The project was supported by the Royal Geographical Society (with the Institute of British Geographers) with the Land Rover Bursary; the Deep Carbon Observatory DECADE Initiative; Ocean Optics; Crowcon; Air Liquide; Thermo Fisher Scientific; Santander; Cactus Outdoor; Turbo Ace and Team Black Sheep. We thank Sebastien Carretier and Rose-Marie Ojeda together with IRD South-America personnel for all their logistical help. We further thank the CONAF and DGAC for their help. YM acknowledges support from the Scripps Institution of Oceanography Postdoctoral Fellowship program. CIS acknowledges a research startup grant from Victoria University of Wellington
    Description: Published
    Description: 237-247
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: volcanic degassing ; Multi-GAS ; UAV ; Trail By Fire ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Present-day uplift of the European Alps: Evaluating mechanisms and models of their relative contributions (2020)
    Elsevier
    Details
    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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  • 8
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    Degassing regime of Hekla volcano 2012–2013 (2020)
    Elsevier
    Details
    Publication Date: 2020-12-18
    Description: Hekla is a frequently active volcano with an infamously short pre-eruptive warning period. Our project contributes to the ongoing work on improving Hekla’s monitoring and early warning systems. In 2012 we began monitoring gas release at Hekla. The dataset comprises semi-permanent near-real time measurements with a MultiGAS system, quantification of diffuse gas flux, and direct samples analysed for composition and isotopes (δ13C, δD and δ18O). In addition, we used reaction path modelling to derive information on the origin and reaction pathways of the gas emissions. Hekla’s quiescent gas composition was CO2-dominated (0.8 mol fraction) and the δ13C signature was consistent with published values for Icelandic magmas. The gas is poor in H2O and S compared to hydrothermal manifestations and syn-eruptive emissions from other active volcanic systems in Iceland. The total CO2 flux from Hekla central volcano (diffuse soil emissions) is at least 44 T d−1, thereof 14 T d−1 are sourced from a small area at the volcano’s summit. There was no detectable gas flux at other craters, even though some of them had higher ground temperatures and had erupted more recently. Our measurements are consistent with a magma reservoir at depth coupled with a shallow dike beneath the summit. In the current quiescent state, the composition of the exsolved gas is substantially modified along its pathway to the surface through cooling and interaction with wall-rock and groundwater. The modification involves both significant H2O condensation and scrubbing of S-bearing species, leading to a CO2-dominated gas emitted at the summit. We conclude that a compositional shift towards more S- and H2O-rich gas compositions if measured in the future by the permanent MultiGAS station should be viewed as sign of imminent volcanic unrest on Hekla.
    Description: The research leading to these results has received funding from the Icelandic Centre for Research (RANNIS, grant number 110002-0031); the European Community’s Seventh Framework Programme under Grant Agreement No. 308377 (Project FUTUREVOLC); and the International Civil Aviation Organization.
    Description: Published
    Description: 80-99
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: Hekla ; Multi-GAS ; degassing ; volcanic unrest ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Tectonics and seismicity in the Northern Apennines driven by slab retreat and lithospheric delamination (2020)
    Elsevier
    Details
    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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