Collezione Completa 2022

PubAIV 2022
(aggiornato ad Aprile 2022)

1) Magmi e sistemi di alimentazione (11 articoli) (+1 articolo)
2) Dinamiche eruttive e di messa in posto (2 articoli)
3) Geologia e struttura dei vulcani (2 articoli) (+1 articolo)
4) Monitoraggio, pericolosità e rischio vulcanico (4 articoli) (+1 articolo)

Tematica 1: Magmi e sistemi di alimentazione
Bonechi B., Gaeta M., Perinelli C., Moschini P., Romano C., Vona A. (2022)
Micro-Raman water calibration in ultrapotassic silicate glasses: Application to phono-tephrites and K-foidites of Colli Albani Volcanic District (Central Italy).
Chemical Geology, 597, 120816
Data di pubblicazione: 25/03/2022
PubAIV-ID-00059 - Articolo in Rivista (non-open access)

This study investigates the potential use of micro-Raman spectroscopy for the quantification of water in ultrapotassic silicate glasses. A calibration was developed using experimental phono-tephritic glasses with water content ranging from ~ 1 to ~ 3 wt%. The calibration curve showed a typical direct proportionality between water content and the ratio of high- (3100–3750 cm−1) and low-wavenumber (100–1500 cm−1) spectral regions, with a linear fit coefficient m = 1.74. The comparison with the m coefficients available in literature for other silicate compositions showed a deviation of our composition as a function of some major oxides such as FeO, TiO2 and K2O, highlighting the possible influence of the polymerization degree (NBO/T: non-bridging oxygens per tetrahedron) on m coefficient. In this respect, we observed a linear relationship between m coefficient and NBO/T and a positive correlation between the area underneath the silicate region (100–1500 cm−1) and NBO/T for the phono-tephrite of this study and for other compositions spanning from basalts to phonolite and rhyolites available in literature. For ultrapotassic natural and experimental glasses characterized by the presence of CO2, documented by the carbonate peak at 1062–1092 cm−1, it has been possible to extrapolate the CO2 content by using the model of Morizet et al. (2013) obtaining values of ~ 1.1 ± 0.3 and ~ 1.7 ± 0.2 wt%, respectively. The obtained m coefficient was applied to estimate water content of natural phono-tephritic glasses belonging to the Colli Albani Volcanic District. Moreover, we estimated water content also for some natural K-foiditic glasses from the same volcanic district. Since the m coefficient results to be strongly dependent on the chemical composition of the sample of interest, the coefficient estimated for the phono-tephrites of this study could result in significant overestimation or underestimation of the water content of the Colli Albani Volcanic District K-foiditic natural samples. Thus, we extrapolated the m coefficient for the K-foiditic samples by means of an equation obtained in this study as function of the polymerization degree (NBO/T).
Bonechi B., Stagno V., Kono Y., Hrubiak R., Ziberna L., Andreozzi G.B, Perinelli C., Gaeta M. (2022)
Experimental measurements of the viscosity and melt structure of alkali basalts at high pressure and temperature.
Scientific Reports, 12, 2599
Data di pubblicazione: 16/02/2022
PubAIV-ID-00053 - Articolo in Rivista (open access)

Volcanic eruptions are shallow phenomena that represent the final stage of density- and viscosity driven processes of melt migration from source rocks at upper mantle depths. In this experimental study, we investigated the effect of pressure (0.7–7.0 GPa) and temperature (1335–2000 °C) on the viscosity and the atomic melt structure of a synthetic anhydrous primitive alkaline basalt, an analogue of the pre-eruptive magma that likely feeds the Campi Flegrei Volcanic District at present day. Obtained viscosities (0.5–3.0 Pa s), mobility (0.1–0.4 g cm3 Pa−1 s−1) and ascent velocity (1.5–6.0 m yr−1)
are presented to support geochemical and geophysical observations of Campi Flegrei as a critical volcanic district currently undergoing gradual magma recharge at depth.
Braschi E., Mastroianni F., Di Salvo S., Casalini M., Agostini S., Vougioukalakis G., Francalanci L. (2022)
Unveiling the occurrence of transient, multi-contaminated mafic magmas inside a rhyolitic reservoir feeding an explosive eruption (Nisyros, Greece).
LITHOS 410–411 (2022) 106574
Data di pubblicazione: 18/12/2021
PubAIV-ID-00050 - Articolo in Rivista (open access)

The investigation of heterogeneous magma systems enhances the understanding of magma differentiation and transfer processes in active volcanoes, thus constraining the dynamics driving the eruptions and the related hazard. Magma heterogeneity is generally preserved in the coeval juvenile products of explosive eruptions, as it occurs in the Upper Pumice sequence, emplaced by the last sub-Plinian explosive eruption at Nisyros volcano (Greece). The deposit comprises a basal fallout, overlaid by pyroclastic density current units, followed by a lag- breccia level. White-yellow, porphyritic, rhyolitic pumices constitute the main juvenile component. Grey, crystal- rich juvenile clasts (CRCs) are less abundant (up to 10–15%), and are characterised by three different texture types (Type-A, -B and -C), with specific recurrence in the different depositional units and well correlated to the magma evolution. In the basal unit CRCs occur as andesitic to dacitic lapilli with Type-A and -B vesicular textures associated with highly variable trace element and isotopic compositions. In the lag-breccia deposit, the juvenile clasts occur as bombs with crenulated or bread-crust surfaces, displaying diktytaxitic Type-C textures and less evolved andesitic compositions, covering a larger Nd-isotope range at lower Sr-isotopes compared to the others.
The CRCs are interpreted as the result of the rapid cooling of more mafic magma blobs sequentially intruded in the cooler rhyolitic host magma, in which they attained variable textures by different undercooling conditions, due to their variable compositions. We suggest that a two-stage AFC (Assimilation plus Fractional Crystallisation) process occurred at different pressures, before intrusion in the host magma, accounting for their heterogeneous chemical and isotopic characteristics. Firstly, the most primitive melts variably assimilated gneissic wallrock at depth, acquiring a variable Nd-isotope signature. On the way to the surface, they later experienced shallow AFC processes within different small magma reservoirs, involving heterogeneous carbonate-rocks such as pure limestone, metasomatised marble and skarn. Sequential dynamics of ascent and intrusion into the rhyolitic magma chamber lead the more evolved and skarn-contaminated Type-A and -B melts to firstly move in the upper part of the reservoir to be erupted in the early fallout deposits. Type-C more mafic melts later intruded the rhyolitic reservoir and were erupted in the lag-breccia deposit. The lowest Nd-isotopes recorded by CRCs, with respect to all the volcanic products of the Kos-Nisyros volcanic field, reveal the peculiar transient history for these magmas at relatively shallow levels in the crust. The CO2 release from the carbonate-rock assimilation has also possibly contributed to trigger the explosive eruption, discharging a large amount of CO2 into the atmosphere.
Corsaro R., Miraglia L. (2022)
Near Real-Time Petrologic Monitoring on Volcanic Glass to Infer Magmatic Processes During the February–April 2021 Paroxysms of the South-East Crater, Etna.
Front. Earth Sci. 10:828026
Data di pubblicazione: 25/02/2022
PubAIV-ID-00056 - Articolo in Rivista (open access)

The South-East crater of Etna (SEC) is the most active summit crater over the last 20 years, producing lava fountains in 2000, 2007–08, and 2011–14. It has been monitored by the INGV Etna Observatory by instrumental networks, field surveys and petrologic monitoring. The syn-eruptive petrologic monitoring consists of an articulated work chain which is generally carried out within 24 h from the moment the sample was emplaced to detect possible changes of magma composition episode by episode, as well as over a longer period. The findings of petrologic monitoring are integrated with the results provided by geophysical networks and gas geochemistry to check the volcano’s behavior during the eruption and to communicate potentially dangerous variations in eruptive features to the local authorities. This paper presents the variation of volcanic glass compositions during the paroxysmal activity of the SEC, which began in
December 2020 and climaxed with 17 episodes from 16 February to 1 April 2021. We infer preeruptive magmatic processes (e.g., fractional crystallization and mixing) based on temporal trends of some key compositional parameters (i.e., CaO/Al2O3; FeOtot/MgO). Correlation between magma dynamics and volcanological characteristics of the paroxysms requires future studies. We demonstrated that petrologic monitoring carried out during a volcanic crisis at Etna, as well as in other volcanoes worldwide, maybe crucial to acquire preliminary insights into the structure of the plumbing system and the pre-eruptive processes governing the eruptive activity. Interestingly, this goal has been achieved also thanks to the collaboration with local citizens, who kindly contributed to collecting samples.
Corsaro R., Branca S., De Beni E., Tanguy J. (2021)
Tales From Three 18th Century Eruptions to Understand Past and Present Behaviour of Etna.
Front. Earth Sci. 9:774361
Data di pubblicazione: 22/12/2021
PubAIV-ID-00057 - Articolo in Rivista (open access)

The structure of an active volcano is highly dependent on the interplay between the geodynamic context, the tectonic assessment as well as the magmatic processes in the plumbing system. This complex scenario, widely explored at Etna during the last 40 years, is nevertheless incomplete for the recent historical activity. In 1763 two eruptions occurred along the west flank of the volcano. There, an eruption started on 6th February and formed the scoria cone of Mt. Nuovo and a roughly 4-km-long lava flow field. Another small scoria cone, known as Mt. Mezza Luna, is not dated in historical sources. It is located just 1 km eastward of Mt. Nuovo and produced a 700mlong flow field. We focused on the activity of Mts. Nuovo and Mezza Luna for several reasons. First, the old geological maps and volcanological catalogues indicate that Mt. Mezza Luna and Mt. Nuovo cones were formed during the same eruption, while historical sources described Mt. Nuovo’s activity as producing a single scoria cone and do not give information about the formation of Mt. Mezza Luna. Second, petrologic studies highlight that the products of Mt. Mezza Luna are
similar to the sub-aphyric Etna basalts; they preserve a composition relatively close to Etna primitive magma which were also erupted in 1763, during La Montagnola flank eruption, which took place along the South Rift of the volcano. Third, the two scoria cones built up along the so-called West Rift of Etna, which represents one of the main magma-ascent zones of the volcano. We applied a multidisciplinary approach that could prove useful for other volcanoes whose past activity is still to be reconstructed. Critical reviews of historical records, new field surveys, petrochemical analyses and petrologic modelling of the Mts. Nuovo and Mezza Luna eruptions have been integrated with literature data. The results allowed improving the stratigraphic record of historical eruptions reported in the Mount Etna Geological map, modelling the sub-volcanic magmatic processes responsible for magma differentiation, and evidencing recurrent mechanisms of magma transfer at Etna. Indeed, the intrusion of a deep primitive magma along the South Rift is often associated
with the activation of other rift zones that erupt residual magma stored in the shallow plumbing system.
Caracciolo A., Halldórsson S.A., Bali E., Marshall E.W., Jeon H., Whitehouse M.J., Barnes J.D., Guðfinnsson G.H., Kahl M., Hartley M.E. (2022)
Oxygen isotope evidence for progressively assimilating trans-crustal magma plumbing systems in Iceland.
Data di pubblicazione: 11/04/2022
PubAIV-ID-00063 - Articolo in Rivista (open access)

The oxygen isotope composition of mantle-derived melts can place important constraints on how magmas are processed as they traverse the crust. Assimilation of crustal material is a crucial aspect of basalt petrogenesis, as it affects the chemical and rheological characteristics of eruptive magmas at active volcanoes. We report oxygen isotope (δ18O) and trace element (TE) data from a suite of well-characterized basaltic melt inclusions and groundmass glasses from the Bárðarbunga volcanic system in Iceland to assess how and where in the plumbing system crustal rocks interact with ascending magmas. While both melt inclusions and groundmass glasses record a large range in δ18O values (+3.2‰ to +6.4‰ and +2.6‰ to +5.5‰, respectively) groundmass glasses record lower values on average. Relationships between incompatible trace element (e.g., Zr/Nb) and oxygen isotope ratios are best explained with three-component mixing, where primary melts derived from depleted and enriched mantle components with distinct δ18O values mix and acquire a low-δ18O character upon progressive contamination with altered Icelandic crust. The majority (60%) of melt inclusions require 10–30% exchange of oxygen with the Icelandic crust. In addition, for the first time, we link the extent of oxygen isotope exchange with melt equilibration depths, showing that most of the contamination occurs at 1–2 kbar (3–7 km depth). We propose that a progressively assimilating, multi-tiered plumbing system is a characteristic feature of the Bárðarbunga volcanic system, whereby chemical modifications resulting from interaction with the crust systematically increase as melts migrate through higher crustal levels. We show that similar processes may also occur across the active rift zone in Iceland.
Godoy B., Taussi M., González-Maurel O., Hübner D., Lister J., Sellés D., le Roux P., Renzulli A., Rivera G., Morata D. (2022)
Evolution of the Azufre volcano (northern Chile): Implications for the Cerro Pabellón Geothermal Field as inferred from long lasting eruptive activity.
Journal of Volcanology and Geothermal Research Volume, 423, 107472
Data di pubblicazione: 01/03/2022
PubAIV-ID-00051 - Articolo in Rivista (non-open access)

Azufre volcano (21°47′S, 68°15′W) is part of the Pleistocene NW-SE trending Azufre-Inacaliri Volcanic Chain, located in the Chilean Central Volcanic Zone of the Andes, near the currently exploited Cerro Pabellón Geothermal Field. Geochronological data and geomorphological features indicate that Azufre was constructed between ~1300 and ~ 120 ka through four magmatic Stages (namely Stage I, II, III and IV), with eruptions from different vents that generated the Northern (Stages II and IV) and Southern (Stages I and III) edifices. Whole rock geochemical data indicates that lavas erupted in Stage II (700–500 ka) and Stage IV (300–120 ka) mainly show lower Al2O3, Na2O and Sr concentrations, and higher FeO, MgO and Ti2O concentrations at similar SiO2 contents than those of Stage I (1,300–700 ka) and Stage III (500–300 ka). These differences suggest dominant plagioclase and Fe–Mg rich mineral phases (i.e. olivine and orthopyroxene) fractionations in the Northern edifice with respect to the Southern one. This is in agreement with petrographic characters that reveal more olivine and orthopyroxene contents in less evolved (hermal Field. This possibly unravels a long lasting (more than 1 Ma) active magmatic system in the northeastern-most sectors of the Azufre-Inacaliri Volcanic Chain and new constraints on the longevity of the heat source regions of the high-enthalpy Cerro Pabellón Geothermal Field, possibly opening new perspectives in the geothermal exploration of this area.
Mangler M.F., Petrone C.M., Prytulak J. (2022)
Magma recharge pattern control eruption styles and magnitudes at Popocatépetl volcano (Mexico).
Data di pubblicazione: 05/01/2021
PubAIV-ID-00048 - Articolo in Rivista (open access)

Diffusion chronometry has produced petrological evidence that magma recharge in mafic to intermediate systems can trigger volcanic eruptions within weeks to months. However, less is known about longer-term recharge frequencies and durations priming magma reservoirs for eruptions. We use Fe-Mg diffusion modeling in orthopyroxene to show that the duration, frequency, and timing of pre-eruptive recharge at Popocatépetl volcano (Mexico) vary systematically with eruption style and magnitude. Effusive eruptions are preceded by 9–13 yr of increased recharge activity, compared to 15–100 yr for explosive eruptions. Explosive eruptions also record a higher number of individual recharge episodes priming the plumbing system. The largest explosive eruptions are further distinguished by an ∼1 yr recharge hiatus directly prior to eruption. Our results offer valuable context for the interpretation of ongoing activity at Popocatépetl, and seeking similar correlations at other arc volcanoes may advance eruption forecasting by including constraints on potential eruption size and style.
Nardini N., Casetta F., Ickert R.B., Mark D.F., Ntaflos T., Zanetti A., Coltorti M. (2022)
From the Middle Triassic Cima Pape complex (Dolomites; Southern Alps) to the feeding systems beneath active volcanoes: Clues from clinopyroxene textural and compositional zoning.
Journal of Volcanology and Geothermal Research, 107459
Data di pubblicazione: 23/12/2021
PubAIV-ID-00047 - Articolo in Rivista (non-open access)

Crystal zoning plays a fundamental role in modern volcanology as a key to unravel the geometry and the dynamics of plumbing systems. In this study, a detailed textural and compositional study of clinopyroxene crystals entrained in intrusive, hypabyssal and effusive products from Cima Pape (Dolomites) is coupled with thermobarometric-hygrometric models to reconstruct the geometry and evolution of the feeding system beneath Middle Triassic volcanic edifices. Whole-rock major, trace element distribution and Sr-Nd isotopic signature (87Sr/86Sri = 0.7045-0.7050; 143Nd/144Ndi = 0.51223-0.51228) show that the rocks from Cima Pape are SiO2-saturated and have shoshonitic affinity, and likely belong to the acme of the Mid-Triassic magmatism that shaped the Southern Alps between 239 and 237.6 Ma. Highly porphyritic trachybasaltic to basaltic trachyandesitic volcanic rocks contain a large number of concentric-zoned clinopyroxene crystals. Here, high-Mg# and -Cr2O3, REE depleted bands (Mg# 80-91; Cr2O3 up to 1.2 wt%) with variable thickness grew between relatively low-Mg# and -Cr2O3 (Mg# 70-77; Cr2O3 conditions of crystallization, occurring at T of 975-1010°C and P comprised between 50 and 150 MPa. Based on the presence of similar zoning in clinopyroxene phenocrysts, a comparison between the Mid-Triassic Cima Pape and active volcanoes was put forward to highlight the potential of studying ancient, entirely exposed volcanic systems for interpreting the feeding system processes acting beneath active volcanoes. At a regional scale, this approach represents a new, powerful tool for investigating the evolution of the Mid-Triassic magmatism in the Southern Alps and shedding light on the interactions between mantle-derived melts and differentiated batches ponding in the crust.
Pichavant M., Di Carlo I., Pompilio M., Le Gall N. (2022)
Textural and petrological features of Stromboli golden pumices require short timescales for paroxysm initiation mechanisms.
Bulletin of Volcanology, 84, 36
Data di pubblicazione: 11/03/2022
PubAIV-ID-00058 - Articolo in Rivista (open access)

New textural and petrological data are presented on products from five paroxysms at Stromboli (Aeolian Islands, Italy) including the two from 2019 and three historical (1930, undated, sixteenth century) eruptions. The data are used to con- strain timescales associated with the initiation of paroxysms and to examine current models for their triggering. Samples were collected from the deposits and a subset selected for mineral separation and petrological and textural characterization. Minerals and glass were imaged by scanning electron microscopy (SEM), and chemical composition and zonation were analysed by electron microprobe. Trace elements in olivine were also determined. Vesicle number densities, vesicularities and vesicle diameters were measured by X-ray microCT techniques. The data were systematically compared with results of experiments simulating, on the one hand, ascent, vesiculation, degassing and crystallization of LP (low-porphyricity) magma and, on the other hand, interaction between LP and HP (high-porphyricity) magma. Paroxysm samples are mixed and include portions representative of both LP and HP magma. They host in variable proportions minerals and glass textur- ally and compositionally typical of these two magma types. Small but systematic variations in matrix glass compositions are found between each of the five eruptions considered. All samples host a population of vesicles ranging from 1000 μm in diameter and whose size distributions follow mixed exponential to power law distributions. Vesicularities are high (75% on average) and vesicle number densities range from 10 2 -10 3 to 10 3 -10 4 mm -3 . Using experimental calibrations, the vesicle textural data suggest average LP magma ascent rates of 1–2 m/s (i.e. ~1.5 hours from depths between 7 and 1.5 km). The correlation between ascent rate and textures demonstrates systematic variations between eruptions, the most ener- getic (i.e. that of 1930) being associated with the highest ascent rate (~2 m/s). Widths of plagioclase reaction zones indicate that LP and HP magmas interacted for a maximum a few hours before eruption. Olivine reaction also implies durations of a few hours for LP-HP interaction and is followed by crystallization for 20 hours in the HP magma. Our results stress the fast ascent of LP magma from their storage region and their short residence times at shallow levels before being erupted. They clarify the respective roles of the deep and shallow feeding systems. An integrated phenomenological model for paroxysm initiation at Stromboli is outlined.
Tommasini S., Bindi L., Savia L., Mangler M.F., Orlando A., Petrone C.M. (2022)
Critical assessment of pressure estimates in volcanic plumbing systems: the case study of Popocatépetl volcano, Mexico.
Lithos, 408-409, 106540
Data di pubblicazione: 28/12/2021
PubAIV-ID-00045 - Articolo in Rivista (non-open access)

Most geobarometers use chemical compositions of minerals and their host melt to estimate crystallization pressures. Crystal structural parameters such as cell and site volumes are not usually considered despite their known sensitivity to pressure. Here, we compare two clinopyroxene geobarometers based upon electron microprobe analysis alone and coupled with single-crystal X-ray diffraction data. The case study is the plumbing system of Popocatépetl volcano (Mexico), which consists of three distinct magma reservoirs in upper, middle and lower crustal depths, represented by three compositionally and texturally distinct clinopyroxene populations (T1, Mg# core 82, and low-Ca with a lower wollastonite component). These clinopyroxenes are augites of limited compositional variability, although yielding a significant increase in cell (V cell) and M1 site (V M1) volumes from low-Ca and T2 core clinopyroxenes to T1 (core and rim) and T2 (rim) clinopyroxenes. This variation is not due to chemical or temperature effects but is linked to their depth of crystallization. The application of the geobarometer based on chemical composition alone is unable to distinguish the three different reservoirs postulated on volcanological and petrological grounds. In contrast, the application of the geobarometer based on both structural parameters and chemical composition yields a remarkable correlation between the calculated cell volume and the estimated depth of crystallization of the different clinopyroxenes, including core to rim differences.

These results have twofold implications. First, the determination of the structural parameters of clinopyroxenes is the only method to resolve the actual distribution of Mg, Fe2+, Fe3+ in the M1 and M2 structural sites and, given the sensitivity of cell and site volumes to pressure, permits to improve geobarometric estimates in volcanic plumbing systems. Second, the quantitative determination of the crystallization depth of the different clinopyroxenes has permitted to rescale the depth of the three different reservoirs in the plumbing system of the Popocatépetl Volcanic Complex located from ~30 km b.s.l. (low-Ca clinopyroxene) to ~18 km b.s.l. (T2 clinopyroxene core) and ~10–0 km b.s.l. (T1 clinopyroxene core and rim, T2 clinopyroxene rim) within the crustal structure of the Morelos platform. This provides further support to the complex plumbing system of the Popocatépetl Volcanic Complex consisting of polybaric storage layers of variable interconnected and interacting transient magma reservoirs.
Tematica 2: Dinamiche eruttive e di messa in posto
Scarani A., Vona A., Di Genova D., Al‑Mukadam R., Romano C., Deubener J. (2022)
Determination of cooling rates of glasses over four orders of magnitude.
Contributions to Mineralogy Petrology, 177, 35
Data di pubblicazione: 01/03/2022
PubAIV-ID-00060 - Articolo in Rivista (open access)

Volcanic materials can experience up to eleven orders of magnitude of cooling rate (qc) starting from 10^(–5) K/s. The glassy component of volcanic material is routinely measured via differential scanning calorimeter (DSC) to obtain qc through the determination of the glass fictive temperature (Tf). Conventional DSC (C-DSC), which has been employed for decades, can only access a relatively small range of qc (from ~10^(–2) to ~1 K/s). Therefore, extrapolations up to six orders of magnitude of C-DSC data are necessary to derive qc of glasses quenched both at extremely low and high qc. Here, we test the reliability of such extrapolations by combining C-DSC with the recently introduced flash calorimetry (F-DSC). F-DSC enables to extend the qc exploration up to 10^4 K/s. We use three synthetic glasses as analogs of volcanic melts. We first apply a normalization procedure of heat flow data for both C-DSC and F-DSC to derive Tf as a function of experimental qc, following the “unified area-matching” approach. The obtained Tf–qc relationship shows that Arrhenius models, widely adopted in previous studies, are only valid for qc determination within the calibration range. In contrast, a non-Arrhenius model better captures qc values, especially when a significant extrapolation is required. We, therefore, present a practical “how-to” protocol for estimating qc using DSC.
Spina L., Cannata A., Morgavi D., Privitera E., Perugini, D. (2022)
Seismo-acoustic gliding: An experimental study.
Earth and Planetary Science Letters, 579, 117344
Data di pubblicazione: 01/02/2022
PubAIV-ID-00054 - Articolo in Rivista (non-open access)

The gradual temporal shift of the spectral lines of harmonic seismic and/or acoustic tremor, known as spectral gliding, has been largely documented at different volcanoes worldwide. Despite the clear advantage of the experimental approach in providing direct observation of degassing processes and related elastic radiation, experimental studies on gliding tremor are lacking. Therefore, we investigated different episodes of gliding of acoustic and seismic tremor observed during analogue degassing experiments performed under different conditions of magma viscosity (10-1,000 Pa s), gas flux (5-180×10−3 l/s) and conduit surface roughness (fractal dimension of 2-2.99). Gliding experimental harmonic seismic and acoustic tremor was observed at high gas flux rates and viscosities, mostly associated with an increasing trend and often preceding a major burst. Decreasing secondary sets of harmonic spectral lines were observed in a few cases. Results suggest that gliding episodes are mostly related to the progressive volume variation of shallow interconnected gas pockets. Spectral analyses performed on acoustic signals provided the theoretical length of the resonator that was compared against the temporal evolution of the gas pockets, quantified from video analyses. The similarities between the observed degassing regime and churn-annular flow in high viscous fluids encourage further studies on churn dynamics in volcanic environments.
Tematica 3: Geologia e struttura dei vulcani
Malaguti A., Rosi M., Pistolesi M., Speranza F., Menzies M. (2021)
The contribution of palaeomagnetism, tephrochronology and radiocarbon dating to refine the last 1100 years of eruptive activity at Vulcano (Italy).
Bullettin of Volcanology, 84(12), 1-19
Data di pubblicazione: 01/01/2022
PubAIV-ID-00046 - Articolo in Rivista (non-open access)

During the past millennia, several eruptions have occurred within the La Fossa caldera on the island of Vulcano (Aeolian Islands, Italy), some being also described in historical documents dating back to Republican Roman times (first to second century BC). The absolute and relative timing of such activity, however, has remained poorly defined and controversial, due to contrasting ages provided by radiometric and unconventional palaeomagnetic methods. Here, we present a detailed recon- struction of the eruptive history focused on the ninth to fifteenth century AD period that occurred at both La Fossa cone and Vulcanello. This integrated approach involves tephrostratigraphy, standard palaeomagnetic methodology and radiocarbon dating. The new dataset confirms that the lavas exposed above sea level at Vulcanello were erupted between the tenth and eleventh century AD, and not between the first and second century BC as previously suggested. In this same time interval, La Fossa cone was characterized by long-lasting, shoshonitic, explosive activity followed by a discrete, sustained, rhyolitic explosive eruption. Between AD 1050 and 1300, activity was focused only on La Fossa cone, with alternating explosive and effusive eruptions that emplaced four rhyolitic and trachytic lava flows, resulting in significant growth of the cone. After the violent, phreatic event of the Breccia di Commenda (thirteenth century), the eruption continued with a substantial, long- lasting emission of fine ash until activity ceased. Magmatic explosive activity resumed at La Fossa cone at the beginning of the fifteenth century marking the onset of the Gran Cratere cycle. This phase lasted until the mid-sixteenth century and produced at least seven explosive eruptions of intermediate magma composition and a couple of lateral explosions (Forgia Vecchia I and II). During this time interval, a third cinder cone was emplaced at Vulcanello, and the activity produced the lava flows of Punta del Roveto and Valle dei Mostri. From the seventeenth to twentieth centuries, volcanic activity was concentrated at La Fossa cone, where it ended in 1890. This work confirms that Vulcanello island formed in Medieval times between the tenth and eleventh centuries. Moreover, between the tenth and mid-sixteenth centuries, La Fossa caldera was the site of at least 19 eruptions with an average eruption rate of one event every 34 years. This rate makes volcanic hazard at Vulcano higher than that suggested to date.
Risica G., Di Roberto A., Speranza F., Del Carlo P., Pompilio M., Meletlidis S., Todrani A. (2022)
Reconstruction of the subaerial Holocene volcanic activity through paleomagnetic and 14C dating methods: El Hierro (Canary Islands).
Journal of Volcanology and Geothermal Research, 425, 107526
Data di pubblicazione: 11/03/2022
PubAIV-ID-00061 - Articolo in Rivista (non-open access)

Volcanic hazard assessment relies on the accurate knowledge of the eruptive style and recurrence of volcanic eruptions in the past. At El Hierro (Canary Islands) historical and prehistorical records are still poorly defined, and although the island was the location of one of the most recent eruptions (La Restinga, 2011 CE) of the Canarian archipelago, the recent subaerial volcanism is still poorly studied. Information about the age of Holocene
volcanic activity as well as the stratigraphy of the deposits is scarce: few eruptions are dated so far, whereas the others are classified as pre-or Holocene events considering lava flow characteristics along the coast.
Here, we report on the dating of eleven (M˜na Chamuscada, M˜na del Tesoro, Orchilla, Las Calcosas, M˜na Negra, Lomo Negro, Below Lomo Negro, Cuchillo del Roque, Malpaso Member, and M˜na del Guanche) Holocene subaerial
eruptions, distributed along the three rift zones, combining paleomagnetic and 14C methods. We also provide geochemical analyses for nine of them. Results indicate that M˜na Chamuscada and M˜na del Tesoro occurred more recently than previously considered, setting them within the last two thousand years. Conversely, paleomagnetic and 14C ages found for Lomo Negro eruption are consistent with literature data (Villasante-Marcos and Pav´on-Carrasco, 2014) and constrain the occurrence of this event in the XVI century CE. Finally, for
Malpaso Member deposits, the two 14C datings obtained by charcoals found below and above the trachytic layer set the eruption during the Holocene epoch, between ~7300 BCE and ~4700 BCE. For the other eruptions, in
two cases (Orchilla and Las Calcosas) many possible time windows during the last 14 ka have been found, whereas a few possible ages have been obtained for the others. On the whole, the resulting chronological reconstruction of the recent activity of El Hierro indicates that eruptions occurred unevenly along the three main rifts, with nine eruptions in the WNW rift, six in the NE rift, and four in the SSE rift. We document at least two periods characterized by high eruptive frequency: an old one, between 8000 BCE and 1000 BCE, with eight
eruptions, three of which characterized by more evolved compositions (phonotephrite and trachyte), and a recent one, between 1000 BCE and present day, with at least seven eruptions, mainly showing basanite compositions. The new data yield a significant improvement of Holocene eruption chronology, thus are instrumental for a correct evaluation of the volcanic hazard at El Hierro.
Tematica 4: Monitoraggio, pericolosità e rischio vulcanico
Campus A., Laiolo M., Massimetti F., Coppola D. (2022)
The Transition from MODIS to VIIRS for Global Volcano Thermal Monitoring.
Sensors, 22, 1713.
Data di pubblicazione: 22/02/2022
PubAIV-ID-00055 - Articolo in Rivista (open access)

The Moderate Resolution Imaging Spectroradiometer (MODIS) is one of the most-used sensors for monitoring volcanoes and has been providing time series of Volcanic Radiative Power (VRP) on a global scale for two decades now. In this work, we analyzed the data provided by the Visible Infrared Imaging Radiometer Suite (VIIRS) by using the Middle Infrared Observation of Volcanic Activity (MIROVA) algorithm, originally developed to analyze MODIS data. The resulting VRP is compared with both the MIROVAMODIS data as well as with the Fire Radiative Power (FRP), distributed by the Fire Information for Resource Management System (FIRMS). The analysis on 9 active volcanoes reveals that VIIRS data analyzed with the MIROVA algorithm allows detecting ~60% more alerts than MODIS, due to a greater number of overpasses (+30%) and improved quality of VIIRS radiance data. Furthermore, the comparison with the nighttime FIRMS database indicates greater effectiveness of the MIROVA algorithm in detecting low-intensity
Massaro S., Rossi E., Sandri L., Bonadonna C., Selva J., Moretti R., Komorowski J-C. (2022)
Assessing hazard and potential impact associated with volcanic ballistic projectiles: The example of La Soufrière de Guadeloupe volcano (Lesser Antilles).
Journal of Volcanology and Geothermal Research 421, 107453
Data di pubblicazione: 13/12/2021
PubAIV-ID-00049 - Articolo in Rivista (open access)

The fallout of ballistic blocks and bombs ejected from eruptive vents has the potential to produce severe injuries to people and damage to infrastructure in areas proximal to volcanoes. The dimensions and dispersions of ballis- tic ejecta from explosive eruptions are pivotal parameters to forecast the potential impact associated with future eruptions based on the compilation of probabilistic hazard maps.
In this study, we propose a new probabilistic hazard quantification strategy to provide the probability of Volcanic Ballistic Projectiles (VBPs) to exceed some critical kinetic energy thresholds, considering a variability on the site of the eruptive vents and the effect of wind. La Soufrière de Guadeloupe (Lesser Antilles) is chosen as a test case, fo- cussing on the most likely explosive scenario associated with the eruption of an active lava dome (including phreatic, Vulcanian and Strombolian eruptions). Sensitivity analyses have guided the optimization of input param- eters to balance the results stability and computational costs, showing that the topography is a pivotal factor when accounting for the spatial uncertainty on vent locations in the proximity of the dome area. Given an eruption within the adopted scenario, we provide maps showing the probability to exceed different energy reference thresholds for roof's perforation if at least one VBP falls in a target area. These maps are then combined with exposed elements to produce a qualitative exposure-based risk map. We compute the overall probability, conditional on the selected scenario, for roof perforation in a given area when a VBP is ejected. Results show probabilities varying from ca. 2% up to 40% within a few km from the volcano, quickly dropping away from the dome. However, when the prob- ability to exceed the energy reference threshold is only conditional on falling of VBPs in a target area, most of Basse- Terre island would be affected by the 20–60% probability of roof perforation. This work confirms how the choice of a probabilistic approach is key to estimate the likelihood of occurrence of VBPs impacts as a first step towards the development and implementation of pro–active risk reduction strategies in volcanic areas.
Monaco L., Palladino D.M., Albert P.G., Arienzo I., Conticelli S., Di Vito M., Fabbrizio A., D'Antonio M., Isaia R., Manning C.J., Nomade S., Pereira A., Petrosino P., Sottili G.,  Sulpizio R., Zanchetta G., Giaccio B. (2022)
Linking the Mediterranean MIS 5 tephra markers to Campi Flegrei (southern Italy) 109–92 ka explosive activity and refining the chronology of MIS 5c-d millennial-scale climate variability.
Global and planetary Change, 211, 103875
Data di pubblicazione: 04/04/2022
PubAIV-ID-00062 - Articolo in Rivista (non-open access)

Explosive activity preceding the ~40 ka Campanian Ignimbrite (CI) eruption in the Neapolitan volcanic area, Southern Italy, has long been speculated based on the occurrences of widespread tephra layers, with a Campanian geochemical signature, such as the C-22, X-5, and X-6, preserved in Mediterranean Marine Isotope Stage (MIS) 5 sedimentary records. However, previous studies of pre-CI pyroclastic units occurring in close proximity of the Neapolitan volcanoes, including Campi Flegrei, Somma-Vesuvius, Ischia and Procida islands, did not allow a conclusive identification of the near-source equivalents of these tephra markers. Here we present a comprehensive characterization of four pyroclastic units from the Campanian Plain, comprising major and trace element glass compositions, Srsingle bondNd isotopes and 40Ar/39Ar dating. Our data allowed the identification of the medial equivalents of the MIS 5 tephra markers, including the widespread C-22, X-5, and X-6 tephra, and their assignment to previously undocumented Campi Flegrei activity between 109 and 92 ka. In addition to substantially extending Campi Flegrei explosive activity deeper in time, and thus providing the basis for a revaluation of its history, our findings provide new precise radioisotopic dating to better constrain the chronology of the millennial scale climatic oscillations of the MIS 5c-d in the Mediterranean area and possibly on a larger scale.
Schito A., Pensa A., Romano C., Corrado S., Vona A., Trolese M., Morgavi D., Giordano G. (2022)
Calibrating Carbonization Temperatures of Wood Fragments Embedded within Pyroclastic Density Currents through Raman Spectroscopy.
Minerals. 2022; 12(2):203
Data di pubblicazione: 05/02/2022
PubAIV-ID-00052 - Articolo in Rivista (open access)

The study of the structural order of charcoals embedded in pyroclastic density currents provides information on their emplacement temperature during volcanic eruptions. In the present work, a set of charcoals from three distinct pyroclastic density currents deposits whose temperatures have been previously estimated by charcoal reflectance analyses to lie between 250 °C and 550 °C, was studied by means of Raman spectroscopy. The analyses reveal a very disordered structural ordering of the charcoals, similar to kerogen matured under diagenetic conditions. Changes in Raman spectra at increasing temperatures reflect depolymerization and an increase of aromaticity and can be expressed by parameters derived from a simplified fitting method. Based on this approach, a second order polynomial regression with a high degree of correlation and a minimum error was derived to predict paleotemperatures of pyroclastic deposits. Our results show that Raman spectroscopy can provide a reliable and powerful tool for volcanological studies and volcanic hazard assessment given its advantage of minimum samples preparation, rapid acquisition processes and high precision.
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