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Ventura, Guido
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Preferred name
Ventura, Guido
Email
guido.ventura@ingv.it
Staff
staff
ORCID
Scopus Author ID
7101605885
Researcher ID
A-6099-2009
146 results
Now showing 1 - 10 of 146
- PublicationOpen AccessAnalisi morfometrica integrata in ambiente GIS applicata ad aree tettonicamente attive come contributo alla valutazione dei rischi ambientali(2007)
; ; ; ; ; ;Nappi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Alessio, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Vilardo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Bellucci Sessa, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ; ; L'obiettivo di questo lavoro è quello di sperimentare e descrivere una metodologia integrata di indagine che possa essere valida per l'analisi delle deformazioni indotte sul territorio dalla tettonica e dalla morfogenesi a scala regionale e locale.266 602 - PublicationRestrictedGeomorphological map of the Somma-Vesuvius volcanic complex (Italy)(2005)
; ; ; ; ; ; ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Vilardo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Bronzino, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Gabriele, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Nappi, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Terranova, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ; ; ; The first geomorphological map of the Somma-Vesuvius active volcano is presented. This map includes the volcanic and epivolcanic landforms at a 1:10.000 scale.The map is obtained combining the available geological information with data derived from: (a) Digital Terrain Model (DTM), (b) image analysis of aerial views and interpretation of topographic maps, (c) field surveys. At Somma-Vesuvius, epivolcanic landforms concentrated in the northern and eastern sectors of the volcano. Volcanic landforms characterize the caldera area, the western and the southern sectors, where the most recent (1631-1944) activity occurred.414 249 - PublicationRestrictedThe effect of particle size on the rheology of liquid-solid mixtures with application to lava flows: Results from analogue experiments(2013-08-02)
; ; ; ;Del Gaudio, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Taddeucci, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; We investigate the effect of crystal size on the rheology of basaltic magmas by means of a rheometer and suspensions of silicon oil with natural magmatic crystals of variable size (from 63 to 0.5 mm) and volume fraction fi (from 0.03 to 0.6). At constant fi, finer suspensions display higher viscosities than coarser ones. Shear thinning (flow index n < 1) occurs at fi > 0.1–0.2 and is more pronounced (stronger departure from the Newtonian behavior) in finer suspensions. Maximum packing and average crystal size displays a nonlinear, positive correlation, while yield stress develops at fi > 0.2–0.3 irrespective of the crystal size. We incorporate our results into physical models for flow of lava and show that, with respect to lava flows containing coarser crystals, those with smaller crystals are expected to: 1) flow at lower velocity, 2) have a lower velocity gradient, and 3) be more prone to develop a region of plug flow. Our experimental results explain the observation that phenocryst-bearing and microlite-bearing lavas at Etna volcano (Italy) show smooth pahoehoe and rough aa’ surfaces, respectively.297 30 - PublicationOpen AccessGeochronology and Petrogenesis of Early Pleistocene Dikes in the Changbai Mountain Volcanic Field (NE China) Based on Geochemistry and Sr-Nd-Pb-Hf Isotopic Compositions(2021)
; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ;Changbai Mountains intraplate volcanism (NE China) developed above the 500 km deep stagnant portion of the Pacific slab in the last 20 Ma. The more recent activity includes a shieldforming stage (2.8–0.3Ma), the Tianchi cone construction stage (1.5–0.01Ma), and a calderaforming stage (0.2Ma-present). Detailed studies on the petrogenesis of the volcanic products between the first two stages and the possible role of geodynamics and local tectonics in controlling the volcanism, however, are lacking. Here, we present structural and whole-rock geochemical and zircon Hf isotopic data on Pleistocene dikes of the Changbai Mountains at the transition from the shield-forming to the Tianchi stage with the aim to constrain their age and the source(s) of their parental magma. The dikes represent the shallower feeding system of monogenetic cones and have a NW-SE strike, which is also the preferred strike of the major fault affecting the area and along which the Changbai Mountains monogenetic scoria cones align. The dikes have a potassic affinity and a trachybasaltic composition. Their zircon U–Pb age is 1.19–1.20Ma (Calabrian). The trachybasalts are enriched in Rb, Ba, Th, U, Nb, Ta, K, Pb, and LREE and slightly depleted in Sr, Zr, Hf, Ti, and HREE with a weak negative Eu/Eu* (δEu 0.96–0.97). Trace elements and isotopic compositions are compatiblewith anOIB-type source with an EMI signature. The calculated (87Sr/86Sr)i ( 0.705165–0.705324), (143Nd/ 144Nd)i ( 0.512552–0.512607, εNd(t) −0.58 to −1.65), and Hf model ages (TDM2) of 1768–1562 Ma suggest that the trachybasaltic dikes were contaminated by a Mesoproterozoic, relatively basic lower crust. The source of the Calabrian trachybasalts consists of asthenospheric melts modified by a subcontinental lithospheric mantle. These melts upwell from depth and stop at the crust-mantle interface where underplating processes favor the assimilation of ancient lower crust material. During the ascent to the surface along deep-seated crustal discontinuities, these magmas weakly differentiate.93 41 - PublicationOpen AccessGeomorphological map of the 1944 Vesuvius lava flow (Italy).(2008)
; ; ;Vilardo, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; The map of the 1944 lava flow shows the geomorphological characteristics of a sector of the Vesuvius volcano (Italy) covered by the products emitted during the last effusive phase. The map has been produced based on the analysis and interpretation of (a) thematic maps (slope, aspect, relative relief) derived from a high resolution (0.33 m pixel) Digital Terrain Model (DTM) obtained by a Airborne Laser Scanning (ASL) survey, and (b) a 1 m pixel digital colour orthophoto. Different flow structures and morphologies have been recognized. The analytical approach proposed here can be used to characterize the smaller scale topographic/geomorphological features of volcanoes and gives constraints on the mechanism of emplacement and modelling strategies of lava flows.192 309 - PublicationOpen AccessRemote sensing of volcanic terrains by terrestrial laser scanner: preliminary reflectance and RGB implications for studying Vesuvius crater (Italy)(2008-08)
; ; ; ;Pesci, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Teza, G.; Universita' Padova ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; This work focuses on the use of terrestrial laser scanner (TLS) in the characterization of volcanic environments. A TLS survey of the Vesuvius crater (Somma-Vesuvius volcano, Italy) allows the construction of an accurate, georeferenced digital model of different sectors of the crater. In each sector, the intensity is computed for each point as the ratio between the emitted amplitude and the received one, normalized to the maximum signal, providing the radiometric information. Moreover, the RGB colours of the observed surfaces can be captured by means of a calibrated camera mounted on the TLS instrument. In this way, multi-band information is given, since a long range TLS operates in the near infrared band. The reflectance and RGB data are compared in order to verify if they are independent enough to be complementary for model analysis and inspection. Results show that the integration of RGB and intensity data can fully characterize this volcanic environment. The collected data are able to discriminate different volcanic deposits and to detect their stratigraphic features. In addition, our results shed light on the spatial extension of landslides and on the dimensions of rock fall/flow deposits affecting the inner walls of the crater. The remotely acquired TLS information from the Vesuvius crater is compared with that from a sedimentary terrain (coal-shale quarry) to detect possible similarities/differences between these two geological environments.229 366 - PublicationOpen AccessThe role of CO2 flushing in triggering the ‘Millennium’ eruption and recent unrests at Changbaishan volcano (China/North Korea)(2022-04)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;The impact of large-scale caldera-forming eruptions on our society and climate can be considerable. The triggering mechanisms of these eruptions and the instability of their magmatic systems are still elusive. Here we use X-ray tomographic microscopy, glass geochemistry and volatile element concentration data on the products of the 946 CE ‘Millennium’ eruption (ME) of Changbaishan volcano (China/North Korea) with the aim to identify the triggering mechanism of the eruption. ME emitted rhyolites and trachytes whose textural parameters suggest vesiculation events related to crystallization and magma ascent in the conduit, and to the arrival of new gas in the magmatic system. Solubility models show that the CO2 and H2O dissolved in the glass are consistent with a pressure of 100–200 MPa. Literature data from fluid inclusions in minerals indicate that the residing magma was CO2 free before the eruption, whereas the CO2 content in the glass reaches 600 ppm at the flash of the ME event. We find that a single, shallow magma reservoir localized between 7.5 and 3.7 km depth in which rhyolites occupies the top and trachytes the bottom is fully destabilized by the arrival of external CO2-rich fluids. Such fluids are released from a deeper, carbonate-rich mantle source. Our results and those of independent geophysical data show that the ME magmatic system is still active, and the continuous upraising of fluids from depth may drive unrest episodes like that recorded in 2002–2006. Our findings elucidate the role of deep, mantle-derived fluids in driving large-scale explosive eruptions. We provide evidence that volcanic unrests may not mirror the internal dynamics of magmatic reservoirs.385 52 - PublicationRestrictedCarbon dioxide Earth degassing and seismogenesis in central and southern Italy(2004)
; ; ; ; ; ; ; ;Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma ;Chiodini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Cardellini, C.; Dipartimento di Scienze della Terra, Universita` di Perugia ;Amato, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia ;Caliro, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Frondini, F.; Dipartimento di Scienze della Terra, Universita` di Perugia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ; ; ; ; We present the first regional map of CO2 Earth degassing from a large area (most of central and south Italy) derived from the carbon of deep provenance dissolved in the main springs of the region. The investigation shows that a globally significant amount of deeply derived CO2 (10% of the estimated global CO2 emitted from subaerial volcanoes) is released by two large areas located in western Italy. The anomalous flux of CO2 suddenly disappears in the Apennine in correspondence to a narrow band where most of seismicity concentrates. Here, at depth, the gas accumulates in crustal traps generating CO2 overpressurized reservoirs which induce seismicity.1053 180 - PublicationOpen AccessAmbient Noise Tomography of the Lipari Volcanic Island (Southern Italy) From a Dense Nodal ArrayWe applied ambient noise tomography to continuous data recorded by a dense seismic array deployed on the volcanic island of Lipari in the southern Tyrrhenian Sea. Since most of Lipari's seismicity occurs offshore and is not evenly distributed, this technique allowed us to obtain the first high-resolution images beneath the island down to ∼2.5 km depth. Results show a complex seismic structure related to the various ages and compositions of the volcanic products characteristic of the different regions of the island. High shear wave velocities are found in western Lipari, where active hydrothermal vents and N-S faults are mapped. Low wave speeds are revealed beneath southern and northeastern Lipari, where more recent volcanic activity developed along N-S dike-like structures that are aligned with rhyolitic vents. We suggest these dikes likely represent the probable pathways of future volcanic eruptions.
67 30 - PublicationRestrictedThe Marsili Ridge (Southern Tyrrhenian Sea, Italy): An island-arc volcanic complex emplaced on a ‘relict’ back-arc basin(2013)
; ; ; ; ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Milano, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Passaro, S. ;Sprovieri, M.; ; ;Marsili Seamount (b1 Ma; Southern Tyrrhenian Sea, Italy) is classically interpreted as the spreading ridge of the about 2 Ma old Marsili oceanic back-arc associated to the Southern Tyrrhenian Sea–Calabrian Arc subduction setting. High resolution bathymetric data show that the ridge extends along a NNE–SSW strike and consists of 4 sectors and 11 major segments. Seafloor failures and central-type activity from an overpressurized sill-like reservoir characterize the central sector, whereas fissural volcanism and passive magma ascent take places at the edges. Cones indicative of high effusion rates concentrate in the axial zone, whereas flat-top shields associated to lower rates are located at the northern tip. Along-axis, lateral magma migration due to a local deepening of the elastic–brittle thickness of the crust develops from the central sector toward the northern tip. The opening of the Marsili back-arc basin vanished from about 1 Ma and the Marsili Ridge formed by passive magma ascent along pre-existing fractures inherited by early spreading activity. The values of the long-term output rate, the ratio between magmatic pressure and tectonic stress, and the morphological features of the lava flows and dikes are consistent with those found in volcanic arc subduction settings. Marsili Ridge represents a volcanic arc edifice emplaced on an older, ‘relict’ back-arc. The formation of the Marsili Ridge marks the transition from an extensional subduction setting to a compressive one.212 45