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  • 1
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    Geophysical precursors of the July-August 2019 paroxysmal eruptive phase and their implications for Stromboli volcano (Italy) monitoring (2020)
    Nature P. G.
    Details
    Publication Date: 2020-06-25
    Description: Two paroxysmal explosions occurred at Stromboli volcano in the Summer 2019, the first of which, on July 3, caused one fatality and some injuries. Within the 56 days between the two paroxysmal explosions, effusive activity from vents located in the summit area of the volcano occurred. No significant changes in routinely monitored parameters were detected before the paroxysmal explosions. However, we have calculated the polarization and the fractal dimension time series of the seismic signals from November 15, 2018 to September 15, 2019 and we have recognized variations that preceded the paroxysmal activity. In addition, we have defined a new parameter, based on RSAM estimation, related to the Very Long Period events, called VLP size, by means of which we have noticed significant variations through the whole month preceding the paroxysm of July 3. In the short term, we have analyzed the signals of a borehole strainmeter installed on the island, obtaining automatic triggers 10 minutes and 7.5 minutes before the July 3 and the August 28 paroxysms, respectively. The results of this study highlight mid-term seismic precursors of paroxysmal activity and provide valuable evidence for the development of an early warning system for paroxysmal explosions based on strainmeter measurements
    Description: This work benefited from funds of the EU (DG ECHO) Project EVE n. 826292 and was partially supported by the project INGV-FISR-2017 “Sale Operative Integrate e Reti di Monitoraggio del Futuro: l’INGV 2.0”. The data used in this study were provided by the Istituto Nazionale di Geofisica e Vulcanologia (Osservatorio Vesuviano, Osservatorio Etneo). The authors are also grateful to the Italian Presidenza del Consiglio dei Ministri- Dipartimento della Protezione Civile (DPC) for supporting the monitoring activities at Stromboli.
    Description: Published
    Description: 10296
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Keywords: Stromboli ; volcano ; precursors ; early warning ; seismic precursor
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Insights Into the Mechanisms of Phreatic Eruptions From Continuous High Frequency Volcanic Gas Monitoring: Rincón de la Vieja Volcano, Costa Rica (2019)
    Details
    Publication Date: 2019-03-01
    Description: Understanding the trigger mechanisms of phreatic eruptions is key to mitigating the effects of these hazardous but poorly forecastable volcanic events. It has recently been established that high-rate volcanic gas observations are potentially very suitable to identifying the source processes driving phreatic eruptions, and to eventually detecting precursory changes prior to individual phreatic blasts. In February-May 2017, we deployed a Multi-GAS instrument to continuously monitor gas concentrations in the crater lake plume of Rincón de la Vieja, a remote and poorly monitored active volcano in Costa Rica, site of frequent phreatic/phreatomagmatic eruptions. Forty-two phreatic/phreatomagmatic eruptions were seismically recorded during our investigated period, 9 of which were also recorded for gas by the Multi-GAS. To the best of our knowledge, these represent the first instrumentally measured gas compositions during individual phreatic/phreatomagmatic explosions at an active volcano. Our results show that during background quiescent degassing the Rincón de la Vieja crater lake plume was characterized by high CO2/SO2 ratios of 64 ± 59 and H2S/SO2 ratios of 0.57 ± 0.20. This composition is interpreted as reflecting hydrothermal (re)processing of magma-sourced gas in the sub-limnic environment. Phreatic blasts were recorded by the Multi-GAS as brief (1–2 min long) pulses of elevated gas mixing ratios (up to ~52 ppmv SO2 and 〉3,000 ppmv CO2), or more than an order of magnitude higher than during background degassing (~1 ppmv SO2 and ~450 ppmv CO2). During the phreatic eruption(s), the H2S/SO2 ratio was systematically lower (〈0.18) than during background degassing, but the CO2/SO2 ratio remained high (and variable), ranging from 37 to 390. These S-poor compositions for the eruptive gas imply extensive processing of the source magmatic gas during pre-eruptive hydrothermal storage, likely by deposition of native S and/or sulfate. Our gas results are thus overall consistent with a mechanism of phreatic eruptions triggered by accumulation of magmatic-hydrothermal gases beneath a hydrothermal seal. We claim that real-time Multi-GAS monitoring is urgently needed at other crater lake-hosting volcanoes (e.g., Ruapehu, Aso), where phreatic eruptions may similarly be preceded by phases of reduced S degassing at the surface.
    Description: Published
    Description: Article 247
    Description: 4V. Dinamica dei processi pre-eruttivi
    Description: JCR Journal
    Keywords: volcanic gases ; crater lakes ; rincon de la vieja ; multi-GAS ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Challenges in UV camera-based real-time SO2 flux monitoring: insights from 5 years of continuous observations at Etna ad Stromboli (2019)
    Miscellanea INGV
    Details
    Publication Date: 2019-01-24
    Description: The advent of UV cameras has recently paved the way to volcanic SO2 flux observations of much improved temporal and spatial resolution, and has thus contributed to expanding use and utility of SO2 fluxes in volcano monitoring. Recently, the first examples of permanent UV camera systems have appeared that are now opening the way to routine fully automated monitoring of the volcanic SO2 flux at high-rate, and continuously (daily hours only). In 2014, using funding from the FP7-ERC project “Bridge” (http://www.bridge.unipa.it/), we deployed a network of 4 permanent UV cameras at Etna and Stromboli volcanoes (Sicily) that has been operating regularly since then. Using a suite of custom-built codes, data streamed by the UV camera are automatically processed and telemetered, allowing nearly real-time visualization and analysis of SO2 fluxes. Here, we summarise the key results obtained during the last 5 years of continuous observations (2014-2018) to demonstrate potentials and challenges in real-time continuous SO2 flux monitoring with UV cameras. We show that the spatially resolved SO2 flux time-series delivered by the UV camera allow effectively tracking migration in volcanic activity from the Central to New South-East Crater (Etna), and shifts in degassing activity along the crater terrace (Stromboli). At both volcanoes, the high temporal of UV cameras allows capturing the escalation in active (strombolian) SO2 degassing that typically precedes onset of paroxysmal (Etna in 2014-2016) or effusive (Stromboli in 2014) activity, and to quantify for the first time the syn- explosive SO2 budget for larger-scale explosions, including 2 paroxysmal lava fountains (Etna) and 1 major explosion (Stromboli). We finally demonstrate the ability of our automatic camera systems to capture temporal changes in SO2 flux regime, and thus to “live” monitoring degassing and eruptive behaviors at active volcanoes.
    Description: Published
    Description: Napoli
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Keywords: UV Camera ; SO2 Flux Monitoring ; Etna ; Stromboli
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 4
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    A SO2 flux study of the Etna volcano 2020–2021 paroxysmal sequences (2024)
    Frontiers S.A.
    Details
    Publication Date: 2024-01-25
    Description: The persistent open-vent degassing of Mt. Etna is often punctuated by monthslong paroxysmal sequences characterized by episodes of violent Strombolian to lava fountaining activity. Understanding these gas-fueled transitions from quiescence to eruption requires routine measurement of gas fluxes. Here, we report SO2 flux measurements, obtained from a permanent UV camera system, collected over a two-year-long period spanning two paroxysmal sequences of Etna’s New South East Crater (NSEC) in December 2020/April 2021 and May/ October 2021. In both cases, SO2 flux increased from ≤ 3250 Mg/day during “ordinary” activity to ≥ 4200 Mg/day. We interpret these distinct SO2 degassing regimes in light of seismic and thermal observations and drawing on numerical simulations of sulfur degassing constrained by parental melt sulfur contents in Etna’s hawaiites. We find that initiation of a paroxysmal sequence results from an approximate doubling of the time-averaged rate of magma supply (and degassing) above the sulfur exsolution level (~150 MPa pressure), to 〉4m3/s. This corroborates recent models that argue for the triggering of paroxysmal sequences by escalating supply of volatile-rich magma to a reservoir ~3–4 km below the summit region. The non-stationary nature of magma flow and volcanic degassing we identify highlights the need for sustained surveillance to characterize long-term atmospheric budgets of volcanic volatiles
    Description: Published
    Description: 1115111
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Etna, ; volcanic gases ; SO2 flux ; paroxysms ; UV Camera ; basaltic explosive volcanism ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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