Giugno 2022

PubAIV 2022
(aggiornamento di Giugno 2022)

1) Magmi e sistemi di alimentazione (2 articoli)
2) Dinamiche eruttive e di messa in posto (0 articoli)
3) Geologia e struttura dei vulcani (0 articoli)
4) Monitoraggio, pericolosità e rischio vulcanico (6 articoli)

Tematica 1: Magmi e sistemi di alimentazione
Brogi F., Colucci S., Matrone J., Montagna C.P., de' Michieli Vitturi M., Papale P. (2022)
MagmaFOAM-1.0: a modular framework for the simulation of magmatic systems.
Geoscientific Model Development, 15, 3773–3796
Data di pubblicazione: 10/05/2022
PubAIV-ID-00069 - Articolo in Rivista (open access)

Numerical simulations of volcanic processes play a fundamental role in understanding the dynamics of magma storage, ascent, and eruption. The recent extraordinary progress in computer performance and improvements in numerical modeling techniques allow simulating multiphase systems in mechanical and thermodynamical disequilibrium. Nonetheless, the growing complexity of these simulations requires the development of flexible computational tools that can easily switch between sub-models and solution techniques. In this work we present MagmaFOAM, a library based on the open-source computational fluid dynamics software OpenFOAM that incorporates models for solving the dynamics of multiphase, multicomponent magmatic systems. Retaining the modular structure of OpenFOAM, MagmaFOAM allows runtime selection of the solution technique depending on the physics of the specific process and sets a solid framework for in-house and community model development, testing, and comparison. MagmaFOAM models thermomechanical nonequilibrium phase coupling and phase change, and it implements state-of-the-art multiple volatile saturation models and constitutive equations with composition-dependent and space–time local computation of thermodynamic and transport properties. Code testing is performed using different multiphase modeling approaches for processes relevant to magmatic systems: Rayleigh–Taylor instability for buoyancy-driven magmatic processes, multiphase shock tube simulations propaedeutical to conduit dynamics studies, and bubble growth and breakage in basaltic melts. Benchmark simulations illustrate the capabilities and potential of MagmaFOAM to account for the variety of nonlinear physical and thermodynamical processes characterizing the dynamics of volcanic systems.
Montagna C.P., Papale P., Longo A. (2022)
Magma Chamber Dynamics at the Campi Flegrei Caldera, Italy.
Orsi, G., D'Antonio, M., Civetta, L. (eds.), Campi Flegrei. Active Volcanoes of the World, Springer, Berlin, Heidelberg, pp 201–217
Data di pubblicazione: 08/02/2022
PubAIV-ID-00070 - Capitolo di Libro (non-open access)

The Campi Flegrei caldera volcanic system is certainly a remarkable case study of magma chamber dynamics. Its magmatic and volcanic history appears to have been largely driven by magma chamber processes like fractional crystallisation, magma mixing, and volatile degassing. These processes have been intensely investigated with a variety of approaches that are described in many chapters of this book, and more specifically, in Chaps. An Evolutionary Model for the Magmatic System of the Campi Flegrei Volcanic Field (Italy) Constrained by Petrochemical Data; Rheological Properties of the Magmas Feeding the Campi Flegrei Caldera (Italy) and Their Influence on Mixing Processes. In this chapter, physical modelling and numerical simulations are employed in order to study the dynamics of magma convection and mixing in a vertically extended, geometrically complex, compositionally heterogeneous magmatic system representing a schematic simplification of an overall picture emerging from previous studies at Campi Flegrei caldera. Although clearly an idealisation, a number of first order characteristics of possible real magmatic systems at Campi Flegrei caldera are accounted for. They include the more chemically evolved, partially degassed nature of magmas emplaced at shallow depths, and the likely occurrence of multiple reservoirs with different depth, size and shape which can be connected at certain stages during system evolution. If that happens, deeper, CO2-rich magmas may rise and rejuvenate the shallow magmas.
Tematica 2: Dinamiche eruttive e di messa in posto
Tematica 3: Geologia e struttura dei vulcani
Tematica 4: Monitoraggio, pericolosità e rischio vulcanico
Di Traglia F., Fornaciai A., Casalbore D., Favalli M., Manzella I., Romagnoli C., Chiocci F.L., Cole P., Nolesini T., Casagli N. (2022)
Subaerial-submarine morphological changes at Stromboli volcano (Italy) induced by the 2019–2020 eruptive activity.
Geomorphology, 400, 108093.
Data di pubblicazione: 03/01/2022
PubAIV-ID-00074 - Articolo in Rivista (open access)

This study analyses the morphological changes induced by eruptive activity at Stromboli volcano (Italy) during and after events occurring during July–August 2019. This period was characterized by intense eruptive activity (two paroxysmal explosions, a two-month-long lava emission, and more intense and frequent “ordinary” explosive activity) that produced significant changes within the region known as Sciara del Fuoco, located on the most unstable, north-western flank of the volcano. Since September 2019, the eruptive activity waned but remained intense, and erosive phenomena continued to contribute to the re-shaping of the Sciara del Fuoco. The morphological changes described here were documented by integrating topographic (PLÉIADES satellite tri-stereo Digital Elevation Models) and multibeam bathymetric data, acquired before, during, and after the paroxysmal events. This allowed the study of the cumulative effect of the different processes and the characterization of the different phases of accumulation/emplacement, erosion, remobilization and re-sedimentation of the volcaniclastic materials.

Data acquired at several periods between September 2018 and April 2020, allowed a comparison of the subaerial and submarine effects of the 2019 events. We find evidence of localized, significant erosion following the two pyroclastic density currents triggered by the paroxysmal explosion of the 3 July 2019. We interpret this erosion as being caused by submarine and subaerial landslides triggered by the propagation of pyroclastic density currents down the Sciara del Fuoco slope. Immediately after the explosion, a lava field accumulated on the sub-aerial slope, produced by effusive activity which lasted about two months. Subsequently, the newly emplaced lava, and in particular its breccia, was eroded, with the transfer of material onto the submarine slope. This work demonstrates how repeated topo-bathymetric surveys allowed identification of the slope processes that were triggered in response to the rapid geomorphological variations due to the eruptive activity. The surveys also allowed distinction of whether estimated volumetric losses were the result of single mass-flows or gradual erosive processes, with implications on the related geohazard. Furthermore, this work highlights how submarine slope failures can be triggered by the entry into the water of pyroclastic density currents, even of modest size. These results are important for the development and improvement of an early warning system for tsunami-induced by mass flows, both in Stromboli and for island-based and coastal volcanoes elsewhere, where landslides and pyroclastic density currents can trigger significant, potentially destructive, tsunami waves.
Galetto, F., Acocella, V., Hooper, A., Bagnari M. (2022)
Eruption at basaltic calderas forecast by magma flow rate.
Nat. Geosci.
Data di pubblicazione: 23/06/2022
PubAIV-ID-00075 - Articolo in Rivista (non-open access)

Forecasting eruption is the ultimate challenge for volcanology. While there has been some success in forecasting eruptions hours to days beforehand, reliable forecasting on a longer timescale remains elusive. Here we show that magma inflow rate, derived from surface deformation, is an indicator of the probability of magma transfer towards the surface, and thus eruption, for basaltic calderas. Inflow rates ≥0.1 km3 yr−1 promote magma propagation and eruption within 1 year in all assessed case studies, whereas rates.
Giudicepietro F., Calvari S., D’Auria L., Di Traglia F., Layer L., Macedonio G., Caputo T., De Cesare W., Ganci G., Martini M., Orazi M., Peluso R., Scarpato G., Spina L., Nolesini T., Casagli N., Tramelli A., Esposito A.M. (2022)
Changes in the Eruptive Style of Stromboli Volcano before the 2019 Paroxysmal Phase Discovered through SOM Clustering of Seismo-Acoustic Features Compared with Camera Images and GBInSAR Data.
Remote Sensing, 14(5),1287.
Data di pubblicazione: 06/03/2022
PubAIV-ID-00071 - Articolo in Rivista (open access)

Two paroxysmal explosions occurred at Stromboli on 3 July and 28 August 2019, the first of which caused the death of a young tourist. After the first paroxysm an effusive activity began from the summit vents and affected the NW flank of the island for the entire period between the two paroxysms. We carried out an unsupervised analysis of seismic and infrasonic data of Strombolian explosions over 10 months (15 November 2018–15 September 2019) using a Self-Organizing Map (SOM) neural network to recognize changes in the eruptive patterns of Stromboli that preceded the paroxysms. We used a dataset of 14,289 events. The SOM analysis identified three main clusters that showed different occurrences with time indicating a clear change in Stromboli’s eruptive style before the paroxysm of 3 July 2019. We compared the main clusters with the recordings of the fixed monitoring cameras and with the Ground-Based Interferometric Synthetic Aperture Radar measurements, and found that the clusters are associated with different types of Strombolian explosions and different deformation patterns of the summit area. Our findings provide new insights into Strombolian eruptive mechanisms and new perspectives to improve the monitoring of Stromboli and other open conduit volcanoes.
Gracchi T., Tacconi Stefanelli C., Rossi G., Di Traglia F., Nolesini T., Tanteri L., Casagli N. (2022)
UAV-Based Multitemporal Remote Sensing Surveys of Volcano Unstable Flanks: A Case Study from Stromboli.
Remote Sensing, 14(10), 2489.
Data di pubblicazione: 23/05/2022
PubAIV-ID-00073 - Articolo in Rivista (open access)

UAV-based photogrammetry is becoming increasingly popular even in application fields that, until recently, were deemed unsuitable for this technique. Depending on the characteristics of the investigated scenario, the generation of three-dimensional (3D) topographic models may in fact be affected by significant inaccuracies unless site-specific adaptations are implemented into the data collection and processing routines. In this paper, an ad hoc procedure to exploit high-resolution aerial photogrammetry for the multitemporal analysis of the unstable Sciara del Fuoco (SdF) slope at Stromboli Island (Italy) is presented. Use of the technique is inherently problematic because of the homogeneous aspect of the gray ash slope, which prevents a straightforward identification of match points in continuous frames. Moreover, due to site accessibility restrictions enforced by local authorities after the volcanic paroxysm in July 2019, Ground Control Points (GCPs) cannot be positioned to constrain georeferencing. Therefore, all 3D point clouds were georeferenced using GCPs acquired in a 2019 (pre-paroxysm) survey, together with stable Virtual Ground Control Points (VGCPs) belonging to a LiDAR survey carried out in 2012. Alignment refinement was then performed by means of an iterative algorithm based on the closest points. The procedure succeeded in correctly georeferencing six high-resolution point clouds acquired from April 2017 to July 2021, whose time-focused analysis made it possible to track several geomorphological structures associated with the continued volcanic activity. The procedure can be further extended to smaller-scale analyses such as the estimation of locally eroded/accumulated volumes and pave the way for rapid UAV-based georeferenced surveys in emergency conditions at the SdF.
Simionato R., Jarvis P. A., Rossi E., Bonadonna C. (2022)
PlumeTraP: A New MATLAB-Based Algorithm to Detect and Parametrize Volcanic Plumes from Visible-Wavelength Images.
Remote Sensing, 14 (7), 1766
Data di pubblicazione: 06/04/2022
PubAIV-ID-00068 - Articolo in Rivista (open access)

Tephra plumes from explosive volcanic eruptions can be hazardous for the lives and livelihoods of people living in the proximity of volcanoes. Monitoring and forecasting tephra plumes play essential roles in the detection, characterization and hazard assessment of explosive volcanic events. However, advanced monitoring instruments, e.g., thermal cameras, can be expensive and are not always available in monitoring networks. Conversely, visible-wavelength cameras are significantly cheaper and much more widely available. This paper proposes an innovative approach to the detection and parametrization of tephra plumes, utilizing videos recorded in the visible wavelengths. Specifically, we have developed an algorithm with the objectives of: (i) identifying and isolating plume-containing pixels through image processing techniques; (ii) extracting the main geometrical parameters of the eruptive column, such as the height and width, as functions of time; and (iii) determining quantitative information related to the plume motion (e.g., the rise velocity and acceleration) using the physical quantities obtained through the first-order analysis. The resulting MATLAB-based software, named Plume Tracking and Parametrization (PlumeTraP), semi-automatically tracks the plume and is also capable of automatically calculating the associated geometric parameters. Through application of the algorithm to the case study of Vulcanian explosions from Sabancaya volcano (Peru), we verify that the eruptive column boundaries are well recognized, and that the calculated parameters are reliable. The developed software can be of significant use to the wider volcanological community, enabling research into the dynamics of explosive volcanic eruptions, as well as potentially improving the use of visible-wavelength cameras as part of the monitoring networks of active volcanoes. Furthermore, PlumeTraP could potentially find a broader application for the analysis of any other plume-shaped natural or anthropogenic phenomena in visible wavelengths.
Turchi A., Di Traglia F., Gentile R., Fornaciai A., Zetti I., Fanti R. (2022)
Relative seismic and tsunami risk assessment for Stromboli Island (Italy).
International Journal of Disaster Risk Reduction, 103002.
Data di pubblicazione: 29/04/2022
PubAIV-ID-00072 - Articolo in Rivista (open access)

An innovative method of estimating the relative risk of buildings exposed to seismic and tsunami hazards in volcanic islands is applied to Stromboli (Italy), a well-known stratovolcano affected by moderate earthquakes and mass-flow-induced tsunamis. The method uses a pre-existing quali-quantitative analysis to assess the relative risk indices of buildings, which provide comparative results useful for prioritisation purposes, in combination with a historical-geographical settlement analysis consistent with the ‘territorialist’ approach to the urban and regional planning and design. The quali-quantitative analysis is based on a new proposed survey-sheet model, useful to collect building information necessary for the relative risk estimation, whereas the historical-geographical investigation is based on the multi-temporal comparison of aerial and satellite images. The proposal to combine two consolidated methods represents an innovation in estimating relative risk. Considering that Stromboli Island had never been subjected to similar analyses, the results of the relative seismic risk assessment are novel and moreover identify buildings with a fairly-low and spatially-uniform relative risk. The results of the relative tsunami risk assessment are consistent with results of similar past studies, identifying buildings with a higher relative risk index on the northern coast of the island. The combined use of a building-by-building survey with a multi-temporal analysis of settlements allows obtaining a higher detail than previously available for the region. If adequately modified, the proposed combination of methods allows assessing relative risk also considering other geo-environmental hazards and their cascading effects, in a multi-hazard risk assessment perspective.
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