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Bonadonna, Costanza
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Bonadonna, Costanza
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- PublicationRestrictedObservations and Retrievals of Volcanic Ash Clouds Using Ground- and Satellite-Based Sensors(2023)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ;This work was born from a wish of remembering the fundamental contribution of Prof. Frank Silvio Marzano to the field of physical volcanology. In fact, for the last fifteen years and in the context of several European projects, Prof. Marzano collaborated with many volcanologists as well as scientists from different fields and wrote many scientific articles aimed at studying the dynamics of explosive eruptions. He left his imprinting in this research sector laying the foundations of radar volcanology in Italy, and extended his studies to other sensors. His work is relevant for the analysis of the main eruption source parameters needed to characterize the eruptive events. Here we show how remote sensing instruments applied to analyze explosive activity of different volcanoes worldwide, are going to increase the knowledge in this multidisciplinary research area and the awareness from the scientific community of the potential of these sensors at various wavelengths.83 1 - PublicationOpen AccessImage analysis of volcanic plumes: A simple calibration tool to correct for the effect of wind(2023)
; ; ; ; ; ; ; ; ; ;; ; ;Video cameras provide vital information on volcanic plumes from explosive eruptions, such as plume height, for monitoring and research. These images must be calibrated to get accurate quantitative data. However, the presence of wind complicates any calibration as the plume may no longer lie in the image plane, i.e. a plane perpendicular to the camera’s line-of-sight. Here, we present a simple new tool to correct for the effect of wind on the position and height of a volcanic plume as determined from imagery by rotating the image plane to be in the direction of the wind. We show the importance of accounting for the effect of wind on the maximum plume height determined from videos for two case-studies; a Vulcanian explosion from Sabancaya volcano, Peru, and a sustained plume from Mount Etna, Italy. This tool can improve the accuracy of quantitative information extracted from images of volcanic plumes, and should prove useful for both research and monitoring purposes.91 19 - PublicationRestrictedDynamics of shallow hydrothermal eruptions: new insights from Vulcano’s Breccia di Commenda eruption(2018-12)
; ; ; ; ; ; ; ; ;; ; Understanding the dynamics and effects of hydrothermal eruptions is crucial to the hazard assessment in both volcanic and geothermal areas. Eruptions from hydrothermal centres may occur associated with magmatic phases, but also as isolated events without magmatic input, with the most recent examples being those of Te Maari (Tongariro, New Zealand) in 2012 and Ontake (Japan) in 2014. The most recent caldera of the Island of Vulcano (southern Italy) hosts in its centre the La Fossa cone, active since 5.5 ka and now characterised by continuous fumarolic degassing. In historical times, La Fossa cone has experienced several hydrothermal eruptions, with the most violent event being the Breccia di Commenda eruption that occurred during the thirteenth century ad. Based on analysis of 170 stratigraphic logs, we show that the Breccia di Commenda eruption occurred in three main phases. After an opening, low-intensity ash emission phase (phase 1), the eruption energy climaxed during phase 2, when a series of violent explosions produced an asymmetric shower of ballistic blocks and the contemporaneous emplacement of highly dispersed, lithic-rich, blast-like pyroclastic density currents (PDCs). The tephra units emplaced during phase 2, ranging in volume from 0.2 to 2.7 × 10^5 m3, were covered in turn by thin ash fall deposits (phase 3). The dynamics of the most violent and intense stage of the eruption (phase 2) was investigated by numerical simulations. A three-dimensional numerical model was applied, describing the eruptive mixture as a Eulerian–Eulerian, two-phase, non-equilibrium gas-particle fluid (plus a one-way coupled Lagrangian ballistic block fraction). At the initial simulation time, a mass of about 10^9 kg, with initial overpressure above 10 MPa, and a temperature of 250 °C, was suddenly ejected from a 200-m-long, eastward inclined, NNE–SSW trending fissure. The mass release formed blast-like PDCs on both sides of the fissure and launched ballistic blocks eastwards. Field investigations and numerical simulations confirm that hydrothermal explosions at La Fossa cone include intense ballistic fallout of blocks, emission of PDCs potentially travelling beyond the La Fossa caldera and significant ash fallout. The hazard associated with both ballistic impact and PDC ingress, as associated with hydrothermal eruption, is significantly larger with respect to that associated with Vulcanian-type events of La Fossa.403 3 - PublicationOpen AccessExamples of Multi-Sensor Determination of Eruptive Source Parameters of Explosive Events at Mount Etna(2021)
; ; ; ; ; ; ; ; ; ; ; ; ; ;; ;; ; ; ;; ;; Multi-sensor strategies are key to the real-time determination of eruptive source parameters (ESPs) of explosive eruptions necessary to forecast accurately both tephra dispersal and deposition. To explore the capacity of these strategies in various eruptive conditions, we analyze data acquired by two Doppler radars, ground- and satellite-based infrared sensors, one infrasound array, visible video-monitoring cameras as well as data from tephra-fallout deposits associated with a weak and a strong paroxysmal event at Mount Etna (Italy). We find that the different sensors provide complementary observations that should be critically analyzed and combined to provide comprehensive estimates of ESPs. First, all measurements of plume height agree during the strong paroxysmal activity considered, whereas some discrepancies are found for the weak paroxysm due to rapid plume and cloud dilution. Second, the event duration, key to convert the total erupted mass (TEM) in the mass eruption rate (MER) and vice versa, varies depending on the sensor used, providing information on different phases of the paroxysm (i.e., unsteady lava fountaining, lava fountain-fed tephra plume, waning phase associated with plume and cloud expansion in the atmosphere). As a result, TEM and MER derived from different sensors also correspond to the different phases of the paroxysms. Finally, satellite retrievals for grain-size can be combined with radar data to provide a first approximation of total grain-size distribution (TGSD) in near real-time. Such a TGSD shows a promising agreement with the TGSD derived from the combination of satellite data and whole deposit grain-size distribution (WDGSD).311 20 - PublicationRestrictedScavenging of sulphur, halogens and trace metals by volcanic ash: The 2010 Eyjafjallajökull eruption(2013)
; ; ; ; ; ; ; ; ;; ; ;; ; ;The Eyjafjallajo¨kull volcanic eruption in 2010 released considerable amounts of ash into the high troposphere-low stratosphere, leading to unprecedented disruption of air traffic over Europe. The role of such fine-grained tephra in adsorbing, and therefore rapidly scavenging, volcanogenic volatile elements such as sulphur and halogens, is explored here. We report on results (major to trace element chemistry) of leaching experiments carried out on 20 volcanic ash samples, taken from the deposits of the main phases of the eruption (March–April 2010), or directly while falling (5–9 May 2010). Ash leachate solutions from Eyjafjallajo¨kull are dominated– among cations– by Ca and Na, and display nearly equal S:Cl:F abundances (mean S/Cl and S/F molar ratios of 0.95 and 0.34, respectively). Abundances of major elements on surface minerals from freshly fallen ash are found to increase linearly upon increasing distance from the eruptive vents (a proxy for in-plume residence times). This allows for the formation rates of sulphur- and halogen-bearing surface salts to be quantified (3 *10- 9 to 2* 10- 8molm2s- 1), and for the averaged rate of in-plume ash-dissolution to be estimated (1.5* 10-8 mol m 2 s- 1; this sourcing the majority of cation species to soluble surface salts). These fast in-plume eterogeneous reactions are the cause of large volatile depositions: we estimate that 282 tons of elemental S, 605 tons of Cl, and 691 tons of F were daily ground depos ited via ash over Iceland in early May 2010. Since fluorine is 3 times more rapidly processed in the plume than S and halogens (e.g., F is extremely reactive both in gas and aerosol forms and it is rapidly adsorbed onto ash), ash leachate compositions are in no way representative of S:Cl:F proportions in volcanic gases, and consequently of limited use in eruption monitoring.24 1 - PublicationOpen AccessThe initial phase of the 2021 Cumbre Vieja ridge eruption (Canary Islands): Products and dynamics controlling edifice growth and collapse(2022)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ;; Tajogaite cone in the Cumbre Vieja ridge (La Palma, Canary Islands) erupted between 19 September and 13 December 2021. The tephra and lava sourced from the newly formed fissure rapidly built a pyroclastic cone. During the early days of eruption and after several small-scale landslides, the west flank of the edifice partially collapsed on 25 September, breaching the cone and emplacing a prominent raft-bearing lava flow. Our research combines direct observations, digital elevation models, thermal and visible imaging, and textural and compositional investigation of the explosive products to describe and characterize the edifice growth and collapse. The cone built over a steep slope (26◦) and its failure occurred after an intense phase of lava fountaining (up to 30 m3 s 1) that produced rapid pyroclastic accumulation. We suggest that an increased magma supply, to an ascent rate of 0.30 m s 1, led to the rapid growth of the cone (at 2.4 × 106 m3 day 1). Simultaneously, the SW lava flow reactivated and formed a lava ‘seep’ that undercut the flank of the cone, triggering a lateral collapse via rotational rockslide that moved at minimum speeds of 34–70 m h 1. The lateral collapse formed a ~ 200 m wide scar, involving 5.5 × 106 m3 of material, and covered 1.17 km2 with decametric edifice portions and raft-bearing lava. The collapse produced a modest change in the vent geometry, but did not affect eruptive activity long term. A short pause in the eruption after the collapse may have been favored by rapid emptying of the shallower magma system, reducing ascent rates and increasing crystallization times. These results reveal the complex chain of events related to the growth and destruction of newly formed volcanic cones and highlight hazards when situated close to inhabited areas.439 26 - PublicationOpen AccessA Model for Buoyant Tephra Plumes Coupled to Lava Fountains With an Application to the 29th of August 2011 Paroxysmal Eruption at Mount Etna, ItalyExplosive basaltic eruptions pose significant threats to local communities, regional infrastructures and international airspace. They produce tephra plumes that are often associated with a lava fountain, complicating their dynamics. Consequently, source parameters cannot be easily constrained using traditional formulations. Particularly, mass flow rates (MFRs) derived from height observations frequently differ from field deposit-derived MFRs. Here, we investigate this discrepancy using a novel integral plume model that explicitly accounts for a lava fountain, which is represented as a hot, coarse-grained inner plume co-flowing with a finer-grained outer plume. The new model shows that a plume associated with a lava fountain has higher variability in rise height than a standard plume for the same initial MFR depending on initial conditions. The initial grain-size distribution and the relative size of the lava fountain compared to the surrounding plume are primary controls on the final plume height as they determine the strength of coupling between the two plumes. We apply the new model to the August 29, 2011 paroxysmal eruption of Mount Etna, Italy. The modeled MFR profile indicates that the field-derived MFR does not correspond to that at the vent, but rather the MFR just above the lava fountain top. High fallout from the lava fountain results in much of the erupted solid material not reaching the top of the plume. This material deposits to form the proximal cone rather than dispersing in the atmosphere. With our novel model, discrepancies between the two types of observation-derived MFR can be investigated and understood.
181 8 - PublicationRestrictedSettling-driven gravitational instabilities associated with volcanic clouds: new insights from experimental investigationsDownward propagating instabilities are often observed at the bottom of volcanic plumes and clouds. These instabilities generate fingers that enhance the sedimentation of fine ash. Despite their potential influence on tephra dispersal and deposition, their dynamics is not entirely understood, undermining the accuracy of volcanic ash transport and dispersal models. Here, we present new laboratory experiments that investigate the effects of particle size, composition and concentration on finger generation and dynamics. The experimental set-up consists of a Plexiglas tank equipped with a removable plastic sheet that separates two different layers. The lower layer is a solution of water and sugar, initially denser than the upper layer, which consists of water and particles. Particles in the experiments include glass beads as well as andesitic, rhyolitic and basaltic volcanic ash. During the experiments, we removed the horizontal plastic sheet separating the two fluids. Particles were illuminated with a laser and filmed with a HD camera; particle image velocimetry (PIV) is used to analyse finger dynamics. Results show that both the number and the downward advance speed of fingers increase with particle concentration in the upper layer, while finger speed increases with particle size but is independent of particle composition. An increase in particle concentration and turbulence is estimated to take place inside the fingers, which could promote aggregation in subaerial fallout events. Finally, finger number, finger speed and particle concentration were observed to decrease with time after the formation of fingers. A similar pattern could occur in volcanic clouds when the mass supply from the eruptive vent is reduced. Observed evolution of the experiments through time also indicates that there must be a threshold of fine ash concentration and mass eruption rate below which fingers do not form; this is also confirmed by field observations.
176 5 - PublicationRestrictedTecolote volcano, Pinacate volcanic field (Sonora, Mexico): A case of highly explosive basaltic volcanism and shifting eruptive stylesExplosive basaltic eruptions have been documented in monogenetic volcanic fields, and recognizing the scales of their explosivity is important for understanding the full range of basaltic volcanism. Here we reconstruct one of the youngest eruptions in the Pinacate volcanic field (Sonora, Mexico) and estimate the volumes of the lava flows, scoria cone, and tephra units. The source vent of the eruption is Tecolote volcano (27 ± 6 ka, 40Ar/39Ar). There were two distinct episodes of tephra production, Tephra Unit 1 (T1) followed by Tephra Unit 2 (T2). T1 and T2 show different dispersal patterns, with T1 dispersed in an approximately circular pattern and T2 dispersed oblately trending SE and NW of the vent. Based on column height reconstructions and deposit characteristics, the T1-producing eruption was subplinian (15–18 km plume), with a calculated mass eruption rate ranging between 1.0 ± 0.6 × 107 kg/s and 2.2 ± 1.2 × 107 kg/s and corresponding durations between 79 ± 54 min and 38 ± 26 min, respectively. The T2-producing eruption was violent Strombolian (11 km plume) with a calculated mass eruption rate of 3.2 ± 1.4 × 106 kg/s and resulting duration of 193 ± 78 min. In addition to the two tephra units, Tecolote volcano produced seven morphologically distinct lava flows. The majority of lava volume production occurred before—and partly contemporaneously with—tephra production, and five small-volume lava flows were emplaced after pyroclastic activity terminated, indicating shifting and simultaneous eruptive styles. Of the total 0.23 km3 dense rock equivalent (DRE) erupted volume, the lava flows constitute the majority (0.17 km3 DRE), with 0.041 km3 DRE volume for the cone and a combined 0.026 ± 0.005 km3 DRE volume for the two tephra units. The geochemistry of the samples is consistent with that determined for other Pinacate rocks, which show a trend most similar to that of ocean island basalts and appears characteristically similar to other volcanic fields of the Basin and Range province
51 3 - PublicationOpen AccessOperational volcanic ash monitoring during Etna volcanic crises(2018-04-08)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Operational systems able to monitor volcanic ash in real time and provide both critical eruption parameters and useful warnings to emergency responders and government agencies should be implemented in most volcanic observatories worldwide. Over the past ten years, more than fifty lava fountains occurred at Mt. Etna (Italy) that produced eruption columns more than 10 km a.s.l. and generated large tephra fallout around the volcano flanks. For civil protection purposes, there was the need to improve the already existing monitoring systems daily run at the Istituto Nazionale di Geofisica and Vulcanologia, mainly based on eruption scenarios (weak and strong plume scenarios). We present a new upgraded system that has multiple objectives: i) to have a fast system able to best identify the type of eruptive scenario; ii) to forecast the tephra deposit in near real time, i.e. within a few hours from the eruptive event; iii) to determine the area impacted by clasts larger than 5 cm that could severely injure hikers, guides, and volcanologists and damage infrastructures in proximity of Etna summit craters. This new system is based on the real-time estimate of column height from the analysis of images taken by SEVIRI satellite and by new calibrated cameras and using meteorological parameters obtained by local models.99 16