Ottobre 2022

PubAIV 2022
(aggiornamento di Ottobre 2022)

1) Magmi e sistemi di alimentazione (0 articoli) 
2) Dinamiche eruttive e di messa in posto (1 articolo)
3) Geologia e struttura dei vulcani (0 articoli)
4) Monitoraggio, pericolosità e rischio vulcanico (4 articoli)

Tematica 1: Magmi e sistemi di alimentazione
Tematica 2: Dinamiche eruttive e di messa in posto
Laiolo M., Delle Donne D., Coppola D.,Bitetto M., Cigolini C., Della Schiava M., Innocenti L., Lacanna G., La Monica F.P., Massimetti F., Pistolesi M., Silengo M.C., Aiuppa A., Ripepe M. (2022)
Shallow magma dynamics at open-vent volcanoes tracked by coupled thermal and SO2 observations.
Earth and Planetary Science Letters, 594, 117726
Data di pubblicazione: 22/07/2022
PubAIV-ID-00083 - Articolo in Rivista (open access)

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.
Tematica 3: Geologia e struttura dei vulcani
Tematica 4: Monitoraggio, pericolosità e rischio vulcanico
Calvari S., Di Traglia F., Ganci G., Bruno V., Ciancitto F., Di Lieto B., Gambino S., Garcia A., Giudicepietro F., Inguaggiato S., Vita F., Cangemi M., Inguaggiato C., Macedonio G., Mattia M., Miraglia L., Nolesini T., Pompilio M., Romano P., Salerno G., Casagli N., Re G., Del Carlo P., Di Roberto A., Cappello A., Corradino C., Amato E., Torrisi F., Del Negro C., Esposito A. M., De Cesare W., Caputo T., Buongiorno M. F., Musacchio M., Romaniello V., Silvestri M., Marotta E., Avino R., Avvisati G., Belviso P. (2022)
Multi-parametric study of an eruptive phase comprising unrest, major explosions, crater failure, pyroclastic density currents and lava flows: Stromboli volcano, 1 December 2020–30 June 2021.
Frontiers in Earth Science
Data di pubblicazione: 22/08/2022
PubAIV-ID-00084 - Articolo in Rivista (open access)

Open conduit volcanoes like Stromboli can display elusive changes in activity before major eruptive events. Starting on December 2020, Stromboli volcano displayed an increasing eruptive activity, that on 19 May 2021 led to a crater-rim collapse, with pyroclastic density currents (PDCs) that spread along the barren NW flank, entered the sea and ran across it for more than 1 km. This episode was followed by lava flow output from the crater rim lasting a few hours, followed by another phase of lava flow in June 2021. These episodes are potentially very dangerous on island volcanoes since a landslide of hot material that turns into a pyroclastic density current and spreads on the sea surface can threaten mariners and coastal communities, as happened at Stromboli on 3 July and 28 August 2019. In addition, on entering the sea, if their volume is large enough, landslides may trigger tsunamis, as occurred at Stromboli on 30 December 2002. In this paper, we present an integration of multidisciplinary monitoring data, including thermal and visible camera images, ground deformation data gathered from GNSS, tilt, strainmeter and GBInSAR, seismicity, SO2 plume and CO2 ground fluxes and thermal data from the ground and satellite imagery, together with petrological analyses of the erupted products compared with samples from previous similar events. We aim at characterizing the preparatory phase of the volcano that began on December 2020 and led to the May–June 2021 eruptive activity, distinguishing this small intrusion of magma from the much greater 2019 eruptive phase, which was fed by gas-rich magma responsible for the paroxysmal explosive and effusive phases of July–August 2019. These complex eruption scenarios have important implications for hazard assessment and the lessons learned at Stromboli volcano may prove useful for other open conduit active basaltic volcanoes.
Casalbore D., Di Traglia F., Romagnoli C., Favalli M., Gracchi T., Tacconi Stefanelli C., Nolesini T., Rossi G., Del Soldato M., Manzella I., Cole P., Casagli N., Chiocci F.L. (2022)
Integration of Remote Sensing and Offshore Geophysical Data for Monitoring the Short-Term Morphological Evolution of an Active Volcanic Flank: A Case Study from Stromboli Island.
Remote Sensing. 2022; 14(18):4605
Data di pubblicazione: 15/09/2022
PubAIV-ID-00086 - Articolo in Rivista (open access)

The Sciara del Fuoco (SdF) collapse scar at Stromboli is an active volcanic area affected by rapid morphological changes due to explosive/effusive eruptions and mass-wasting processes. The aim of this paper is to demonstrate the importance of an integrated analysis of multi-temporal remote sensing (photogrammetry, COSMO-SkyMed Synthetic Aperture Radar amplitude image) and marine geophysical data (multibeam and side scan sonar data) to characterize the main morphological, textural, and volumetric changes that occurred along the SdF slope in the 2020–2021 period. The analysis showed the marked erosive potential of the 19 May 2021 pyroclastic density current generated by a crater rim collapse, which mobilized a minimum volume of 44,000 m3 in the upper Sciara del Fuoco slope and eroded 350,000–400,000 m3 of material just considering the shallow-water setting. The analysis allowed us also to constrain the main factors controlling the emplacement of different lava flows and overflows during the monitored period. Despite the morphological continuity between the subaerial and submarine slope, textural variations in the SdF primarily depend on different processes and characteristics of the subaerial slope, the coastal area, the nearshore, and “deeper” marine areas.
Di Traglia F., Borselli L., Nolesini T., Casagli N. (2022)
Crater-rim collapse at Stromboli volcano: understanding the mechanisms leading from the failure of hot rocks to the development of glowing avalanches.
Nat Hazards (2022)
Data di pubblicazione: 26/09/2022
PubAIV-ID-00085 - Articolo in Rivista (open access)

The failures of volcanic crater-rims frequently lead to the development of avalanches of glowing rocks, a hybrid phenomenon between rock avalanches and pyroclastic density currents, reaching considerable distances from the eruptive centres and therefore be a serious threat for inhabited areas. The collapse conditions have been here taken in to account by means of slope stability analysis using a Limit Equilibrium Method analysis on the crater-rim of Stromboli volcano (Italy). A Stromboli, crater-rim collapses occurred frequently (at least seven events in the last two decades) and were always associated with high-level of magma within the conduits, testified by the increased eruptive activity and ground-deformation. The more frequent/intense eruptive activity produced a greater accumulation of volcaniclastic material, whereas the high level of magma increased magmastatic thrust on the deposits. Volcaniclastic material was modelled by combining the nonlinear failure envelopes as the Generalized Hoek and Brown criterion, with the addition of the failure's envelope of the rockfill-like material described by the Barton-Kjaernsli criterion, taking into consideration the presence of discontinuities within proximal, partially welded, volcaniclastic masses. In addition to the lithological and morphological characteristics of the crater terrace rim and the magmatic thrust, the effects of the explosions in terms of seismic ground acceleration and disturbance factor (D) of the volcaniclastic material were also considered here. While the ground acceleration compatible with the explosive activity of Stromboli has little influence on the stability of the crater terrace rims, the increase in D increases the proneness for failure.
Langer H., Falsaperla S., Spampinato S., Messina A. (2022)
Energy threshold changes in volcanic activity at Mt. Etna (Italy) inferred from volcanic tremor.
Scientific Reports volume 12, 17895 (2022)
Data di pubblicazione: 25/10/2022
PubAIV-ID-00087 - Articolo in Rivista (open access)

From the 2010s on, pattern classification has proven an effective method for flagging alerts of volcano unrest before eruptive activity at Mt. Etna, Italy. The analysis has been applied online to volcanic tremor data, and has supported the surveillance activity of the volcano that provides timely information to Civil Protection and other authorities. However, after declaring an alert, no one knows how long the volcano unrest will last and if a climactic eruptive activity will actually begin. These are critical aspects when considering the effects of a prolonged state of alert. An example of longstanding unrest is related to the Christmas Eve eruption in 2018, which was heralded by several months of almost continuous Strombolian activity. Here, we discuss the usage of thresholds to detect conditions leading to paroxysmal activity, and the challenges associated with defining such thresholds, leveraging a dataset of 52 episodes of lava fountains occurring in 2021. We were able to identify conservative settings regarding the thresholds, allowing for an early warning of impending paroxysm in almost all cases (circa 85% for the first four months in 2021, and over 90% for the whole year). The chosen thresholds also proved useful to predict that a paroxysmal activity was about to end. Such information provides reliable numbers for volcanologists for their assessments, based on visual information, which may not be available in bad weather or cloudy conditions.
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