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  • 1
  • 2
    Publication Date: 2022-01-01
    Print ISSN: 0301-0104
    Electronic ISSN: 1873-4421
    Topics: Chemistry and Pharmacology , Physics
    Published by Elsevier
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  • 3
    Publication Date: 2023-01-16
    Description: Open-vent volcanic activity is typically sustained by ascent and degassing of shallow magma, in which the rate of magma supply to the upper feeding system largely exceeds the rate of magma eruption. Such unbalance between supplied (input) and erupted (output) magma rates is thought to result from steady, degassing-driven, convective magma overturning in a shallow conduit/feeding dyke. Here, we characterize shallow magma circulation at Stromboli volcano by combining independent observations of heat (Volcanic Radiative Power; via satellite images) and gas (SO2 , via UV camera) output in a temporal interval (from August 1, 2018 to April 30, 2020) encompassing the summer 2019 effusive eruption and two paroxysmal explosions (on July 3 and August 28, 2019). We show that, during the phase of ordinary strombolian explosive activity that preceded the 2019 effusive eruption, the average magma input rate (0.1-0.2 m3 /s) exceeds the magma eruption rate (0.001-0.01 m3 /s) by ∼2 orders of magnitude. Conversely, magma input and output rates converge to an average of ∼0.4 m3 /s during the summer 2019 summit effusion, implying an overall suppression of magma recycling back into the feeding system, and hence of excess degassing. We find that, during the effusive eruption, the peak in SO2 emissions lags behind the thermal emission peak by ∼27 days, suggesting that magma output, feeding the lava flow field, initially dominates over magma input in the conduit. We propose that this conduit mass unloading, produced by this initial phase of the effusive eruption, leads to an overall decompression (of up to 30 Pa/s) of the shallow plumbing system, ultimately causing ascent of less-dense, volatile-rich magma batch(es) from depth, enhanced explosive activity, and elevated SO2 fluxes culminating into a paroxysmal explosion on August 28. Our results demonstrate that combined analysis of thermal and SO2 flux time-series paves the way to improved understanding of shallow magmatic system dynamics at open-vent volcanoes, and of the transition from explosive to effusive activity regimes.
    Description: Published
    Description: 117726
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2023-01-16
    Description: ASHER, a new sensor for the characterization of tephra fallout in real time, was designed and developed for easy field deployment during volcanic eruptions. It can provide information on the accumulation rate of tephra fallout in real time as well as grain-size and settling velocity of falling particles. Particle detection is achieved with a laser barrier, with size and settling velocity being calculated from the amplitude and duration of obscuration peaks. The sampling rate (31,500 Hz), laser thickness (0.5 mm) and operation (ON/OFF state and dual acquisition mode) are adapted to minimize the noise level and allow detection of particles as small as ~100 μm. Additional measurements of weight and level of accumulated material within a removable collector allow broadening of the ASHER operation to accumulation rate from 10−2 to 103 g m-2s-1. Detailed calibration tests were performed in laboratory conditions on single grains of known shape and density along with a high-speed camera to test the capability to measure grain size and terminal velocity, and during two field campaigns at Stromboli and Etna volcanoes to test the operation in the field. Long-term field deployment has shown that combining the optical barrier with an automatic collector allows for a better characterization of tephra fallout, providing an estimate of density, and, therefore, it optimizes sensor operation and minimizes false alerts. Moreover, the low power requirements and onboard processing allows to operate the sensor remotely and solely on solar power in a remote location. Although technical improvements in sensor sensitivity and processing are still possible, the results presented suggest that ground sensors for real-time detection and analysis of tephra could potentially contribute to understanding the dynamics of explosive eruptions and could be successfully integrated into monitoring systems of active volcanoes.
    Description: Published
    Description: 107611
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2023-01-16
    Description: Improving volcanic gas monitoring techniques is central to better understanding open-vent, persistently degassing volcanoes. SO2 cameras are increasingly used in volcanic gas studies, but observations are commonly limited to one single camera alone viewing the volcanic plume from a specific viewing direction. Here, we report on high frequency (0.5 Hz) systematic measurements of the SO2 flux at Stromboli, covering a 1-year long observation period (June 2017-June 2018), obtained from two permanent SO2 cameras using the same automated algorithm, but imaging the plume from two different viewing directions. Our aim is to experimentally validate the robustness of automatic SO2 camera for volcano monitoring and to demonstrate the advantage of using two co-exposed SO2 camera stations to better capturing degassing dynamics at open-vent volcanoes. The SO2 flux time-series derived from the two SO2 camera stations exhibit good match, demonstrating the robustness of the automatic SO2 camera method. Our high-temporal resolution SO2 records resolve individual Strombolian explosions as transient, repetitive gas bursts produced by the sudden release of over pressurized gas pockets and scoriae. Calculations show that explosive degassing activity accounts for ∼10% of the total SO2 emission budget (dominated by passive degassing) during mild regular open-vent activity. We show that the temporal variations of the explosive SO2 flux go in tandem with changes in total SO2 flux and VLP seismicity, implicating some commonality in the source processes controlling passive degassing and explosive activity. We exploited the spatial resolution of SO2 camera to discriminate degassing at two distinct regions of the crater area, and to minimize biases due by the station position respect to the target plume. We find that the SO2 fluxes from southwest-central (SWCC) and northeast (NEC) crater areas oscillate coherently but those from the NEC are more sensitive to the changes in the volcanic intensity. We interpret this as due to preferential gas/magma channeling into the structurally weaker north-eastern portion of the crater terrace in response to increasing supply rate of buoyant, bubble-rich magma in the shallow plumbing system.
    Description: Published
    Description: 972071
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2023-01-16
    Description: The benign fuming activity of dormant volcanoes is punctuated by phases of escalating degassing activity that, on some occasions, ultimately prelude to eruption. However, understanding the drivers of such unrest is complicated by complex interplay between magmatic and hydrothermal processes. Some of the most comprehensively characterised degassing unrest have recently been observed at La Fossa cone on Vulcano Island, but whether or not these episodes involve new, volatile-rich ascending magma remains debated. Here, we use volcanic gas measurements, in combination with melt inclusion information, to propose that heightened sulphur dioxide flux during the intense fall 2021 La Fossa unrest is sourced by degassing of volatile-rich mafic magma. Calculations using a numerical model indicate observations are consistent with the unrest being triggered by the emplacement of ∼3·106 m3 of mafic magma at ∼4–5 km depth. Degassing of mafic magma is argued as a recurrent driver of unrest at dormant volcanoes worldwide.
    Description: Published
    Description: 255
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2023-02-20
    Description: The eruption of the volcano Hunga Tonga-Hunga Ha‘apai on Jan 15, 2022, 04:14:54 UTC, was such energetic that instruments observed different physical phenomena all over the globe. In Italy, the Istituto Nazionale di Geofisica e Vulcanologia (INGV), who is continuously operating different kinds of monitoring networks, as e.g., the Italian Seismic Network (ISN), micro-barometric and infrasonic stations for monitoring the active volcanoes, ionospheric monitoring network (GNSS and ionosonde), recorded seismic, acoustic and electromagnetic signals originated by this exceptional event. The blast wave generated by the volcanic explosion of Hunga Tunga was recorded by the micro-barometric and infrasound stations installed at Phlegrean Fields (PF), at Stromboli volcano and on Mt. Etna. The first arrival was recorded at ~20:00 UTC, after travelling along the “short” great circle (17600 km), was succeeded by a second onset, about 3:40 h later, arriving at PF from the opposite direction. The mean propagation velocity in both directions was calculated as 310 m/s. The stations of the Etna Radio Observatory (ERO) are also equipped with micro-barometers, measuring the atmospheric pressure at a sampling rate of 5 min. The first group of atmospheric shock waves was recorded in the evening of Jan 15, 2022, while 36 hours later the ERO-stations observed a second signal after having completed the second orbit. The magnitude of M5.7 of the Hunga Tonga eruption was strong enough to record core phases (PKIKP, PKP), surface reflection of mantle phases (PP, SS), as well as Rayleigh and Love waves, at many stations of the ISN. The atmospheric waves generated by the eruption generated Travelling Ionospheric Disturbances in the ionosphere detected as disturbances in the Total Electron Content calculated by using GNSS data acquired by the GNSS network of INGV and variations of the ionospheric peak layer parameters (foF2, hmF2), recorded by the ionosonde installed on the Italian territory by INGV.
    Description: Published
    Description: Bellevue, Washington
    Description: 5V. Processi eruttivi e post-eruttivi
    Keywords: Hunga Tonga ; volcanic eruption
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 8
    Publication Date: 2024-01-26
    Description: We used two and a half years long SO2 flux record, obtained using permanent ultraviolet cameras, to characterize changes in degassing dynamics at Mt. Etna volcano from summer 2014 to the end of 2016. Volcanic activity at Mt. Etna was characterized by persistent open-vent degassing periodically interrupted by intense paroxysmal lava fountaining events (in August 2014, December 2015, and May 2016). Results revealed systematic SO2 emission patterns prior, during, and after Etna’s paroxysmal phases, allowing us to identify thresholds between pre-syn-and post-eruptive degassing regimes. The SO2 flux typically peaked during a lava fountain: in the 18 May 2016 example, the averaged SO2 degassing rate was ~158 kg/s, the peak emission was ~260 kg/s, and the total released SO2 mass was ~1700 tons (in 3h). Paroxysmal explosive activity at NSE crater on 11-15 August 2014 was also associated with intense syneruptive SO2 degassing (at 30-40 kg/s levels on a daily average), and was preceded by onset in degassing activity at the same crater 4 days before. During paroxysmal activity on 3-5 December 2015, the SO2 fluxes peaked at 54-103 kg/s from VOR crater, and was preceded by a sizable increase from 10 kg/s (end of November) up to 45.5 kg/s, two days before. The May 16-25 2016 paroxysmal activity was characterized by intense degassing ~2 times higher than the 2016 average (~18 kg/s) and preceded by mild but detectable SO2 flux increases more than one month before its onset. Taken together, our observations, when combined with independent geophysical (thermal and seismic) evidence, allow us to fully characterize the Etna’s degassing dynamics and contribute to our understanding of its shallow plumbing system.
    Description: Published
    Description: Catania
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Keywords: SO2 ; Mt. Etna volcano ; permanent ultraviolet cameras
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Abstract
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  • 9
    Publication Date: 2024-01-25
    Description: The persistent open-vent degassing of Mt. Etna is often punctuated by monthslong paroxysmal sequences characterized by episodes of violent Strombolian to lava fountaining activity. Understanding these gas-fueled transitions from quiescence to eruption requires routine measurement of gas fluxes. Here, we report SO2 flux measurements, obtained from a permanent UV camera system, collected over a two-year-long period spanning two paroxysmal sequences of Etna’s New South East Crater (NSEC) in December 2020/April 2021 and May/ October 2021. In both cases, SO2 flux increased from ≤ 3250 Mg/day during “ordinary” activity to ≥ 4200 Mg/day. We interpret these distinct SO2 degassing regimes in light of seismic and thermal observations and drawing on numerical simulations of sulfur degassing constrained by parental melt sulfur contents in Etna’s hawaiites. We find that initiation of a paroxysmal sequence results from an approximate doubling of the time-averaged rate of magma supply (and degassing) above the sulfur exsolution level (~150 MPa pressure), to 〉4m3/s. This corroborates recent models that argue for the triggering of paroxysmal sequences by escalating supply of volatile-rich magma to a reservoir ~3–4 km below the summit region. The non-stationary nature of magma flow and volcanic degassing we identify highlights the need for sustained surveillance to characterize long-term atmospheric budgets of volcanic volatiles
    Description: Published
    Description: 1115111
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Etna, ; volcanic gases ; SO2 flux ; paroxysms ; UV Camera ; basaltic explosive volcanism ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2022-01-31
    Description: This volume investigates how historiography became a “profession” from the 13th to the 15th century. As a genre, historiography is difficult to define: inspired by Cicero’s rhetorical rules, humanists were the first to elaborate a specific ars. In doing so, they adapted rhetoric to a new ethical sense of humanitas. Several contributors to this book have already discussed in previous works of theirs the linguistic and rhetorical choices that some important historians made. See, for instance, Tra storiografia e retorica: prospettive nel basso medioevo italiano, ed. M. Zabbia, in «Reti Medievali. Rivista», 19 (2018), especially the papers by Paolo Garbini, Marino Zabbia, and Fulvio Delle Donne. On this occasion, they pay attention to the authors’ direct interventions: their self-representation and reflections on methodological issues reveal a new consciousness, which gradually developed over the centuries. This volume is a part of the PRIN project (the acronym standing for Project of Relevant National Interest) titled “A.L.I.M. (Digital Archive of the Italian Latinity in the Middle Ages: http://www.alim.dfll.univr.it): Practices and theory for computer archiving and philology applied to medieval texts”, which Professor Fulvio Delle Donne coordinates at the University of Basilicata.
    Keywords: Antonio Bonfini Medieval historiography ; Cronache medievali ; Franciscus Pipinus ; Biondo Flavio ; Authorship ; Galvannus Flamma ; Francesco Pipino ; Medieval chronicles ; Peter of Eboli ; Goffredo Malaterra ; Galvano Fiamma ; Gaufridus Malaterra ; Pietro da Eboli ; Storiografia medievale ; Tommaso Chaula ; Thomas de Chaula BLondus Flavius Antonius Bonfini ; autorialità
    Language: Italian
    Format: application/octet-stream
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