The bright side of the plume: VOlcanic LighTning and Ash plume electrification

Informations projet

VOLTA

N° de convention de subvention: 864052

DOI

10.3030/864052

Date de signature de la CE 17 Novembre 2020

Date de début 1 Février 2022

Date de fin 31 Janvier 2027

Financé au titre de

• EXCELLENT SCIENCE - European Research Council (ERC)

Coût total

€ 1 999 681,00

Contribution de l’UE

€ 1 999 681,00

Coordonné par

LUDWIG-MAXIMILIANS-UNIVERSITAET MUENCHEN
Germany

Periodic Reporting for period 2 - VOLTA (The bright side of the plume: VOlcanic LighTning and Ash plume electrification)

Période du rapport: 2023-08-01 au 2025-01-31

Résumé du contexte et des objectifs généraux du projet

Electrostatics permeates our life just as it does in volcanic plumes, driving processes from the micro to the global scale. Charging impacts the way ash is transported, sedimented and remobilized, and how it chemically reacts in the environment thus contributing on how ash impacts humans, the environment and infrastructures. Like in thunderclouds, volcanic lightning can be readily detected from safe distance, allowing for real-time mapping of ash plumes.
The ground-breaking hypothesis of VOLTA is that electrification is an intrinsic property of all volcanic plumes and that by measuring it we can derive first-order eruption source parameters which are otherwise inaccessible but at the same time important for the prediction and mitigation of volcanic ash hazard. The current lack of observational and experimental data on the electrification of volcanic eruptions is hindering our basic knowledge of these phenomena.
The overall objective of VOLTA is hence to untangle the tight-knit relation between plume electrification and plume dynamics integrating multi-parametric observation of electrification at active volcanoes with experiments and models on the microphysics of particle charging and particle-laden jets. This unprecedented interdisciplinary approach will integrate physical and experimental volcanology, atmospheric sciences, electrostatics and electrical engineering with the overarching goal of delivering a comprehensive electrical model of volcanic plumes and, consequently, provide a novel and robust tool for real-time volcano monitoring.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

The VOLTA project was implemented successfully in project period 1. Major achievements include: 1) the realization of a prototype version (smaller scale) of the LEAP apparatus for electrification experiments under controlled atmospheres (WP2.1- Task 2.1 and 2.2); 2) the realization of two measurement cells for resistivity measurements of volcanic ash particles (WP2 - Task 3.2); 3) the acquisition and modification of the thunderstorm antennas for electric field measurements (WP1 - Task 1.1); 4) the acquisition of a portable high-speed camera deployable in the field as well as a low resolution infrared thermal camera for field measurements (WP1 - Task 1.1); 5) the acquisition of the infrasound array (WP1 - Task 1.1). The instrumental acquisitions are functional to the completion of the VILMA multiparametric array (WP1 Task 1.1) which is ready to be deployed in the field.
Two successful field campaigns have been conducted at Stromboli and Etna volcano in Italy were electrification of different types of explosive activities have been recorded (WP1 - Task 1.2).These include the first ever measurement of electrical activity produced during pyroclastic density currents, one of the deadliest volcanic hazard. A third field campaign allowed the continuous recording of electrical activity produced during the Tajogaite eruption of Cumbre Vieja volcano on the island of La Palma in the Canary Islands. This is the first continuous measurement ever done at a monogenetic volcano covering the whole duration (over three months) of its eruption. Most importantly our measurements show that variation of the explosive activity (intensity and ash production) are reflected by changes in electrical activity and that a correlation is possible between electric signatures and explosive styles.
Two further campaigns have been conducted with the scope of measuring electrical activity associated to the eruption of geysers at Strokkur geyser in Iceland and Whakarewarewa geyser field in New Zealand (WP1 - Task 1.3). This measurments also constitute a premiere and reveal the ability of water jets to carry electrical charge that can be correlated with the magnitude and intensity of the water explosions. Our results show that water in the volcanic plume can contribute to the electification of the eruptive column even in absence of solid ash particles.
High voltage and high current experiments have been conducted at the Bundeswehr Universität in Munich where experimental fulgurites have been produced under controlled conditions to study the effect of lightning on geological material and in particular the modification of volcanic ash (WP3 - Task 3.3). In particular, the experiments show the impact of different phases of a lightning flash on the melting of sediments and volcanic ash. Our results suggest that the ability of melt production during a lightning event is related to the presence of a continuing current phase following the high current peak phase. By contrary the high-current peak alone seems to be insufficient in producing the necessary heat to enable melting.
The results of VOLTA have been so far published in 7 open-access peer-reviewed publications and disseminated at international and national conferences including EGU, AGU, IAVCEI, the 759th WE-Heraeus-Seminar, the German yearly Physics of Volcanoes meetings as well as invited talks in Universities. The project members of VOLTA have so far co-authored 23 conference contributions.
Further dissemination of the activity and scientific results of VOLTA is achieved through the dedicated website www.volta-erc.com and the twitter account @volta_erc (WP5).

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

All the results achieved so far constitute a progress beyond the state of the art in volcano electrification studies. In particular we are exploring the lower end (in term of magnitude and intensity) of electric activity in explosive eruptions, thus confirming our starting hypothesis on the ubiquitous nature of volcanic electrification. We are extending this to other popular volcanic manifestations such as geysers, for which electrical properties had not been investigated so far, further showing the role played by water in its liquid and gaseous phases in electrification of multiphase jets. Further exploring volcano manifestations, our experiments simulating eruptions at mud volcanoes have shown how discharges generated by self charging of fine particles in methane rich jets in the atmosphere can constitute a possible mechanism of self ignition. Experimental generation of fulgurites in high-current and high-voltage experiments show the ability of production of melting in rocks hit by lightning flashes only in presence of sufficiently long continuing currents. Our study is the first in evidencing this relationship.
In the future development of the project, we expect to collect more evidence of volcanic electrification at active volcanoes and in the laboratory in order to better constrain its phenomenology and derive more quantitative relations to be implemented in numerical models.

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