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Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques

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A special issue of Remote Sensing (ISSN 2072-4292).

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 39994

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Special Issue Editors

Dr. Sonia Calvari

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Guest Editor

Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, 95125 Catania, Italy
Interests: volcanology; volcano monitoring; thermal imagery; lava flows; explosive volcanic activity; instability of volcanoes; hazard assessment
Special Issues, Collections and Topics in MDPI journals

Dr. Alessandro Bonaccorso

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Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, 95125 Catania, Italy
Interests: physical volcanology; volcano deformation; volcano sources modelling

Dr. Annalisa Cappello

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Guest Editor

Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, 95125 Catania, CT, Italy
Interests: thermal remote sensing; data fusion; lava flow modelling
Special Issues, Collections and Topics in MDPI journals

Dr. Flora Giudicepietro

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Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, 80124 Napoli, Italy
Interests: volcano seismicity; geophysical precursors of eruptions; volcano monitoring; experimental geophysics; dynamics of active and dormant volcanoes
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Dr. Eugenio Sansosti

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Istituto per il Rilevamento Elettromagnetico dell’Ambiente (IREA), National Research Council (CNR) of Italy, via Diocleziano, 328, 80124 Naples, Italy
Interests: remote sensing; synthetic aperture radar; InSAR; subsidence; radar signal processing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Volcanoes are complex systems that deserve a multidisciplinary monitoring effort in order to carry out appropriate and timely hazard assessments. In recent years, a number of monitoring techniques based on remotely sensed data have been implemented that enable obtaining synoptic views over the monitored areas. On the other hand, ground-based methods provide punctual, yet more accurate, measurements that complement remotely sensed parameters. It is clear, therefore, that the synergic use of remote sensing techniques and data with ground-based measurements can potentially provide an extra contribution to the hazard assessment, for instance in terms of accuracy of results, amount of information obtained, temporal availability, and so on.

We are seeking contributions that integrate the use of remote sensing and ground-based data, with particular focus on and reference to volcanic processes monitoring and related hazard assessment. In particular, contributions that contain the intersection of and integration between the various terrestrial geophysical monitoring techniques (i.e., seismic, ground deformation), remote sensing both from the ground (i.e., thermal analysis, gas geochemistry) and from satellite (i.e., InSAR, thermal analysis, etc.) are welcome and strongly encouraged. The investigative approach characterized by the integration of disciplines at different scales of vision and precision represent a modern challenge to strive for a more complete understanding of volcanic processes and therefore a better hazard evaluation.

Dr. Sonia Calvari
Dr. Alessandro Bonaccorso
Dr. Annalisa Cappello
Dr. Flora Giudicepietro
Dr. Eugenio Sansosti
Guest Editors

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Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Remote Sensing is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Volcano monitoring
Data integration
Ground based measurements
Satellite observations
Thermal monitoring
Volcanic hazard assessment
InSAR
Volcanic crises management
Explosive and effusive eruptions

Published Papers (13 papers)

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Editorial

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4 pages, 184 KiB

Open AccessEditorial

Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques

by Sonia Calvari, Alessandro Bonaccorso, Annalisa Cappello, Flora Giudicepietro and Eugenio Sansosti

Remote Sens. 2022, 14(15), 3626; https://doi.org/10.3390/rs14153626 - 29 Jul 2022

Cited by 1 | Viewed by 1150

Abstract

The monitoring of active volcanoes is a complex task based on multidisciplinary and integrated analyses that use ground, drones, and satellite monitoring devices [...] Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

Research

Jump to: Editorial

25 pages, 8470 KiB

Open AccessArticle

Comparison between Automated and Manual Detection of Lava Fountains from Fixed Monitoring Thermal Cameras at Etna Volcano, Italy

by Sonia Calvari and Giuseppe Nunnari

Remote Sens. 2022, 14(10), 2392; https://doi.org/10.3390/rs14102392 - 16 May 2022

Cited by 30 | Viewed by 2752

Abstract

The Etna volcano is renowned worldwide for its extraordinary lava fountains that rise several kilometers above the vent and feed eruptive columns, then drift hundreds of kilometers away from the source. The Italian Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Etneo (INGV-OE) is responsible for the monitoring of Mt. Etna, and for this reason, has deployed a network of visible and thermal cameras around the volcano. From these cameras, INGV-OE keeps a keen eye, and is able to observe the eruptive activity, promptly advising the civil protection and aviation authorities of any changes, as well as quantifying the spread of lava flows and the extent of pyroclastic and ash plumes by using a careful analysis of the videos recorded by the monitoring cameras. However, most of the work involves analysis carried out by hand, which is necessarily approximate and time-consuming, thus limiting the usefulness of these results for a prompt hazard assessment. In addition, the start of lava fountains is often a gradual process, increasing in strength from Strombolian activity, to intermediate explosive activity, and eventually leading to sustained lava fountains. The thresholds between these different fields (Strombolian, Intermediate, and lava fountains) are not clear cut, and are often very difficult to distinguish by a manual analysis of the images. In this paper, we presented an automated routine that, when applied to thermal images and with good weather conditions, allowed us to detect (1) the starting and ending time of each lava fountain, (2) the area occupied by hot pyroclasts, (3) the elevation reached by the lava fountains over time, and (4) eventually, to calculate in real-time the erupted volume of pyroclasts, giving results close to the manual analysis but more focused on the sustained portion of the lava fountain, which is also the most dangerous. This routine can also be applied to other active volcanoes, allowing a prompt and uniform definition of the timing of the lava fountain eruptive activity, as well as the magnitude and intensity of the event. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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26 pages, 7986 KiB

Open AccessArticle

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

by Flora Giudicepietro, Sonia Calvari, Luca D’Auria, Federico Di Traglia, Lukas Layer, Giovanni Macedonio, Teresa Caputo, Walter De Cesare, Gaetana Ganci, Marcello Martini, Massimo Orazi, Rosario Peluso, Giovanni Scarpato, Laura Spina, Teresa Nolesini, Nicola Casagli, Anna Tramelli and Antonietta M. Esposito

Remote Sens. 2022, 14(5), 1287; https://doi.org/10.3390/rs14051287 - 6 Mar 2022

Cited by 5 | Viewed by 2379

Abstract

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. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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25 pages, 7755 KiB

Open AccessArticle

The Extensive Parameters as a Tool to Monitoring the Volcanic Activity: The Case Study of Vulcano Island (Italy)

by Salvatore Inguaggiato, Fabio Vita, Iole Serena Diliberto, Agnes Mazot, Lorenzo Calderone, Andrea Mastrolia and Marco Corrao

Remote Sens. 2022, 14(5), 1283; https://doi.org/10.3390/rs14051283 - 5 Mar 2022

Cited by 23 | Viewed by 3610

Abstract

On Vulcano Island (Italy), many geochemical crises have occurred during the last 130 years of solfataric activity. The main crises occurred in 1978–1980, 1988–1991, 1996, 2004–2007, 2009–2010 and the ongoing 2021 anomalous degassing activity. These crises have been characterized by early signals of resuming degassing activity, measurable by the increase of volatiles and energy output emitted from the summit areas of the active cone, and particularly by increases of gas/water ratios in the fumarolic area at the summit. In any case, a direct rather than linear correspondence has been observed among the observed increase in the fluid output, seismic release and ground deformation, and is still a subject of study. We present here the results obtained by the long-term monitoring (over 13 years of observations) of three extensive parameters: the SO₂ flux monitored in the volcanic plume, the soil CO₂ flux and the local heat flux, monitored in the mild thermal anomaly located to the east of the high-temperature fumarole. The time variations of these parameters showed cyclicity in the volcanic degassing and a general increase in the trend in the last period. In particular, we focused on the changes in the mass and energy output registered in the period of June–December 2021, to offer in near-real-time the first evaluation of the level and duration of the actual exhalative crisis affecting Vulcano Island. In this last event, a clear change in degassing style was recorded for the volatiles emitted by the magma. For example, the flux of diffused CO₂ from the soils reached the maximum never-before-recorded value of 34,000 g m⁻² d⁻¹ and the flux of SO₂ of the plume emitted by the fumarolic field on the summit crater area reached values higher than 200 t d⁻¹. The interpretation of the behavior of this volcanic system, resulting from the detailed analyses of these continuous monitoring data, will complete the framework of observations and help in defining and possibly forecasting the next evolution of the actual exhaling crisis. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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24 pages, 66358 KiB

Open AccessEditor’s ChoiceArticle

Integration of DInSAR Time Series and GNSS Data for Continuous Volcanic Deformation Monitoring and Eruption Early Warning Applications

by Brianna Corsa, Magali Barba-Sevilla, Kristy Tiampo and Charles Meertens

Remote Sens. 2022, 14(3), 784; https://doi.org/10.3390/rs14030784 - 8 Feb 2022

Cited by 8 | Viewed by 3513

Abstract

With approximately 800 million people globally living within 100 km of a volcano, it is essential that we build a reliable observation system capable of delivering early warnings to potentially impacted nearby populations. Global Navigation Satellite System (GNSS) and satellite Synthetic Aperture Radar (SAR) document comprehensive ground motions or ruptures near, and at, the Earth’s surface and may be used to detect and analyze natural hazard phenomena. These datasets may also be combined to improve the accuracy of deformation results. Here, we prepare a differential interferometric SAR (DInSAR) time series and integrate it with GNSS data to create a fused dataset with enhanced accuracy of 3D ground motions over Hawaii island from November 2015 to April 2021. We present a comparison of the raw datasets against the fused time series and give a detailed account of observed ground deformation leading to the May 2018 and December 2020 volcanic eruptions. Our results provide important new estimates of the spatial and temporal dynamics of the 2018 Kilauea volcanic eruption. The methodology presented here can be easily repeated over any region of interest where an SAR scene overlaps with GNSS data. The results will contribute to diverse geophysical studies, including but not limited to the classification of precursory movements leading to major eruptions and the advancement of early warning systems. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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25 pages, 14275 KiB

Open AccessArticle

Detailed Cartography of Cotopaxi’s 1877 Primary Lahar Deposits Obtained by Drone-Imagery and Field Surveys in the Proximal Northern Drainage

by S. Daniel Andrade, Emilia Saltos, Valeria Nogales, Sebastián Cruz, Gareth Lee and Jenni Barclay

Remote Sens. 2022, 14(3), 631; https://doi.org/10.3390/rs14030631 - 28 Jan 2022

Cited by 3 | Viewed by 2509

Abstract

Cotopaxi is an active volcano in Ecuador, whose eruptions are characterized by producing destructive primary lahars which represent a major risk for the country. The hazard assessment related to such lahars relies largely on the knowledge of the latest event, which occurred on 26 June 1877, for either scenario definition or simulation calibration. A detailed (1:5000 scale) cartography of the deposits belonging to that eruption has been obtained in the proximal northern drainage of Cotopaxi. The cartography was performed through a combination of geological fieldwork, as well as the analysis and interpretation of high-definition imagery obtained by drone surveys combined with the Structure from Motion technology for image processing. Such imagery included red and green visible bands, and a near-infrared band, which allowed the obtention of NDVI imagery where the primary lahar deposits were identified and cartographed with support of fieldwork data. Both data sources are mutually complementary, and the final cartography would be impossible if any of them were not available. The results obtained represent a significant advance for the level of detail with respect to previous cartographic works. Moreover, they should allow an improved calibration of the new generation of numerical models that simulate lahar flow for hazard assessment at Cotopaxi. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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24 pages, 22381 KiB

Open AccessArticle

A New Analysis of Caldera Unrest through the Integration of Geophysical Data and FEM Modeling: The Long Valley Caldera Case Study

by Fabio Pulvirenti, Francesca Silverii and Maurizio Battaglia

Remote Sens. 2021, 13(20), 4054; https://doi.org/10.3390/rs13204054 - 11 Oct 2021

Cited by 2 | Viewed by 1985

Abstract

The Long Valley Caldera, located at the eastern edge of the Sierra Nevada range in California, has been in a state of unrest since the late 1970s. Seismic, gravity and geodetic data strongly suggest that the source of unrest is an intrusion beneath the caldera resurgent dome. However, it is not clear yet if the main contribution to the deformation comes from pulses of ascending high-pressure hydrothermal fluids or low viscosity magmatic melts. To characterize the nature of the intrusion, we developed a 3D finite element model which includes topography and crust heterogeneities. We first performed joint numerical inversions of uplift and Electronic Distance Measurement baseline length change data, collected during the period 1985–1999, to infer the deformation-source size, position, and overpressure. Successively, we used this information to refine the source overpressure estimation, compute the gravity potential and infer the intrusion density from the inversion of deformation and gravity data collected in 1982–1998. The deformation source is located beneath the resurgent dome, at a depth of 7.5 ± 0.5 km and a volume change of 0.21 ± 0.04 km³. We assumed a rhyolite compressibility of 0.026 ± 0.0011 GPa⁻¹ (volume fraction of water between 0% and 30%) and estimated a reservoir compressibility of 0.147 ± 0.037 GPa⁻¹. We obtained a density of 1856 ± 72 kg/m³. This density is consistent with a rhyolite melt, with 20% to 30% of dissolved hydrothermal fluids. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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23 pages, 5931 KiB

Open AccessArticle

Anatomy of a Paroxysmal Lava Fountain at Etna Volcano: The Case of the 12 March 2021, Episode

by Sonia Calvari, Alessandro Bonaccorso and Gaetana Ganci

Remote Sens. 2021, 13(15), 3052; https://doi.org/10.3390/rs13153052 - 3 Aug 2021

Cited by 24 | Viewed by 3614

Abstract

On 13 December 2020, Etna volcano entered a new eruptive phase, giving rise to a number of paroxysmal episodes involving increased Strombolian activity from the summit craters, lava fountains feeding several-km high eruptive columns and ash plumes, as well as lava flows. As of 2 August 2021, 57 such episodes have occurred in 2021, all of them from the New Southeast Crater (NSEC). Each paroxysmal episode lasted a few hours and was sometimes preceded (but more often followed) by lava flow output from the crater rim lasting a few hours. In this paper, we use remote sensing data from the ground and satellite, integrated with ground deformation data recorded by a high precision borehole strainmeter to characterize the 12 March 2021 eruptive episode, which was one of the most powerful (and best recorded) among that occurred since 13 December 2020. We describe the formation and growth of the lava fountains, and the way they feed the eruptive column and the ash plume, using data gathered from the INGV visible and thermal camera monitoring network, compared with satellite images. We show the growth of the lava flow field associated with the explosive phase obtained from a fixed thermal monitoring camera. We estimate the erupted volume of pyroclasts from the heights of the lava fountains measured by the cameras, and the erupted lava flow volume from the satellite-derived radiant heat flux. We compare all erupted volumes (pyroclasts plus lava flows) with the total erupted volume inferred from the volcano deflation recorded by the borehole strainmeter, obtaining a total erupted volume of ~3 × 10⁶ m³ of magma constrained by the strainmeter. This volume comprises ~1.6 × 10⁶ m³ of pyroclasts erupted during the lava fountain and 2.4 × 10⁶ m³ of lava flow, with ~30% of the erupted pyroclasts being remobilized as rootless lava to feed the lava flows. The episode lasted 130 min and resulted in an eruption rate of ~385 m³ s⁻¹ and caused the formation of an ash plume rising from the margins of the lava fountain that rose up to 12.6 km a.s.l. in ~1 h. The maximum elevation of the ash plume was well constrained by an empirical formula that can be used for prompt hazard assessment. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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31 pages, 4385 KiB

Open AccessArticle

Examples of Multi-Sensor Determination of Eruptive Source Parameters of Explosive Events at Mount Etna

by Valentin Freret-Lorgeril, Costanza Bonadonna, Stefano Corradini, Franck Donnadieu, Lorenzo Guerrieri, Giorgio Lacanna, Frank Silvio Marzano, Luigi Mereu, Luca Merucci, Maurizio Ripepe, Simona Scollo and Dario Stelitano

Remote Sens. 2021, 13(11), 2097; https://doi.org/10.3390/rs13112097 - 27 May 2021

Cited by 23 | Viewed by 3564

Abstract

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). Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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22 pages, 5932 KiB

Open AccessArticle

Submarine and Subaerial Morphological Changes Associated with the 2014 Eruption at Stromboli Island

by Daniele Casalbore, Federico Di Traglia, Alessandro Bosman, Claudia Romagnoli, Nicola Casagli and Francesco Latino Chiocci

Remote Sens. 2021, 13(11), 2043; https://doi.org/10.3390/rs13112043 - 22 May 2021

Cited by 10 | Viewed by 2469

Abstract

Stromboli is an active insular volcano located in the Southern Tyrrhenian Sea and its recent volcanic activity is mostly confined within the Sciara del Fuoco (SdF, hereafter), a 2-km wide subaerial–submarine collapse scar, which morphologically dominates the NW flank of the edifice. In August-November 2014, an effusive eruption occurred along the steep SdF slope, with multiple lava flows reaching the sea. The integration of multisensor remote sensing data, including lidar, photogrammetric, bathymetric surveys coupled with SAR amplitude images collected before and after the 2014 eruption enabled to reconstruct the dynamics of the lava flows through the main morphological changes of the whole SdF slope. Well-defined and steep-sided ridges were created by lava flows during the early stages of the eruption, when effusion rates were high, favoring the penetration into the sea of lava flows as coherent bodies. Differently, fan-shaped features were emplaced during the declining stage of the eruption or in relation to lava overflows and associated gravel flows, suggesting the prevalence of volcaniclastic breccias with respect to coherent lava flows. The estimated volume of eruptive products emplaced on the SdF slope during the 2014 eruption, accounts for about 3.7 × 10⁶ m³, 18% of which is in the submarine setting. This figure is different with respect to the previous 2007 eruption at Stromboli, when a large lava submarine delta formed. This discrepancy can be mainly related to the different elevation of the main vents feeding lava flows during the 2007 eruption (around 400 m) and the 2014 eruption (around 650 m). Besides slope accretion, instability processes were detected both in the subaerial and submarine SdF slope. Submarine slope failure mobilized at least 6 × 10⁵ m³ of volcaniclastic material, representing the largest instability event detected since the 2007 lava delta emplacement. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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30 pages, 15522 KiB

Open AccessArticle

Variable Magnitude and Intensity of Strombolian Explosions: Focus on the Eruptive Processes for a First Classification Scheme for Stromboli Volcano (Italy)

by Sonia Calvari, Flora Giudicepietro, Federico Di Traglia, Alessandro Bonaccorso, Giovanni Macedonio and Nicola Casagli

Remote Sens. 2021, 13(5), 944; https://doi.org/10.3390/rs13050944 - 3 Mar 2021

Cited by 21 | Viewed by 3997

Abstract

Strombolian activity varies in magnitude and intensity and may evolve into a threat for the local populations living on volcanoes with persistent or semi-persistent activity. A key example comes from the activity of Stromboli volcano (Italy). The “ordinary” Strombolian activity, consisting in intermittent ejection of bombs and lapilli around the eruptive vents, is sometimes interrupted by high-energy explosive events (locally called major or paroxysmal explosions), which can affect very large areas. Recently, the 3 July 2019 explosive paroxysm at Stromboli volcano caused serious concerns in the local population and media, having killed one tourist while hiking on the volcano. Major explosions, albeit not endangering inhabited areas, often produce a fallout of bombs and lapilli in zones frequented by tourists. Despite this, the classification of Strombolian explosions on the basis of their intensity derives from measurements that are not always replicable (i.e., field surveys). Hence the need for a fast, objective and quantitative classification of explosive activity. Here, we use images of the monitoring camera network, seismicity and ground deformation data, to characterize and distinguish paroxysms, impacting the whole island, from major explosions, that affect the summit of the volcano above 500 m elevation, and from the persistent, mild explosive activity that normally has no impact on the local population. This analysis comprises 12 explosive events occurring at Stromboli after 25 June 2019 and is updated to 6 December 2020. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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23 pages, 5100 KiB

Open AccessArticle

Plume Height Time-Series Retrieval Using Shadow in Single Spatial Resolution Satellite Images

by Sophie Pailot-Bonnétat, Andrew J. L. Harris, Sonia Calvari, Marcello De Michele and Lucia Gurioli

Remote Sens. 2020, 12(23), 3951; https://doi.org/10.3390/rs12233951 - 3 Dec 2020

Cited by 10 | Viewed by 2609

Abstract

Volcanic plume height is a key parameter in retrieving plume ascent and dispersal dynamics, as well as eruption intensity; all of which are crucial for assessing hazards to aircraft operations. One way to retrieve cloud height is the shadow technique. This uses shadows cast on the ground and the sun geometry to calculate cloud height. This technique has, however, not been frequently used, especially not with high-spatial resolution (30 m pixel) satellite data. On 26 October 2013, Mt Etna (Sicily, Italy) produced a lava fountain feeding an ash plume that drifted SW and through the approach routes to Catania international airport. We compared the proximal plume height time-series obtained from fixed monitoring cameras with data retrieved from a Landsat-8 Operational Land Imager image, with results being in good agreement. The application of the shadow technique to a single high-spatial resolution image allowed us to fully document the ascent and dispersion history of the plume–cloud system. We managed to do this over a distance of 60 km and a time period of 50 min, with a precision of a few seconds and vertical error on plume altitude of ±200 m. We converted height with distance to height with time using the plume dispersion velocity, defining a bent-over plume that settled to a neutral buoyancy level with distance. Potentially, the shadow technique defined here allows downwind plume height profiles and mass discharge rate time series to be built over distances of up to 260 km and periods of 24 h, depending on vent location in the image, wind speed, and direction. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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26 pages, 6160 KiB

Open AccessFeature PaperArticle

Overflows and Pyroclastic Density Currents in March-April 2020 at Stromboli Volcano Detected by Remote Sensing and Seismic Monitoring Data

by Sonia Calvari, Federico Di Traglia, Gaetana Ganci, Flora Giudicepietro, Giovanni Macedonio, Annalisa Cappello, Teresa Nolesini, Emilio Pecora, Giuseppe Bilotta, Veronica Centorrino, Claudia Corradino, Nicola Casagli and Ciro Del Negro

Remote Sens. 2020, 12(18), 3010; https://doi.org/10.3390/rs12183010 - 16 Sep 2020

Cited by 30 | Viewed by 4276

Abstract

Between 28 March and 1 April 2020, Stromboli volcano erupted, with overflows from the NE crater rim spreading along the barren Sciara del Fuoco slope and reaching the sea along the NW coast of the island. Poor weather conditions did not allow a detailed observation of the crater zone through the cameras monitoring network, but a clear view of the lower slope and the flows expanding in the area allowed us to characterize the flow features. This evidence was integrated with satellite, GBInSAR, and seismic data, thus enabling a reconstruction of the whole volcanic event, which involved several small collapses of the summit cone and the generation of pyroclastic density currents (PDCs) spreading along the slope and on the sea surface. Satellite monitoring allowed for the mapping of the lava flow field and the quantification of the erupted volume, and GBInSAR continuous measurements detected the crater widening and the deflation of the summit cone caused by the last overflow. The characterization of the seismicity made it possible to identify the signals that are associated with the propagation of PDCs along the volcano flank and, for the first time, to recognize the signal that is produced by the impact of the PDCs on the coast. Full article

(This article belongs to the Special Issue Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques)

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