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Gruppo di Ricerca in Vulcanologia

HEATED - PHreatic Eruptions at AcTive volcanoEs: processes, source parameters and physical models of eruption Dynamics.

RC

 

https://rdcu.be/dSuk4

From: Montanaro et al. Bull Volcanol. 84, 2022 - https://rdcu.be/dSuk4

 

Phreatic eruptions s.l. derive from the sudden expansion of pressurized fluids generally hosted in hydrothermal systems. Heating by direct contact with magma or magmatic fluids during unrest phases at active volcanoes is the most common cause of phreatic activity. The dynamics of these eruptions involve a rapid acceleration of gas-rock fragments mixture, that is dispersed over limited areas forming thin deposits of ash fallout, ballistic blocks and pyroclastic density currents. Fragmentation is driven by fluid expansion and only involve the hydrothermal system and the overlying rocks, although also juvenile magma fragments can be sporadically ejected. Despite the limited areal impacted, phreatic activity can represent a very high risk at volcanoes in densely populated areas or with a high tourist vocation, also due to the difficult forecasting of this activity. The present state of unrest at two Italian volcanoes (Campi Flegrei; Vulcano island) has evidenced the importance and the need of defining more in detail the dynamics and the possible scenarios of this type of eruptions, that represent at the moment one of the most likely events expected in case of sudden reactivation of the explosive activity at these two volcanoes.

Although the importance of these eruptions in terms of risk is universally recognised, especially after some deadly recent events, the products of phreatic activity have been poorly studied in the past, mainly due to their low preservation potential. Starting from the study of the products of some selected eruptions from Campi Flegrei, Vulcano Island, Nisyros as well as other possible case-studies, the present proposal is aimed at defining the main parameters controlling the occurrence of phreatic eruptions and to assess and model the main physical processes which control the dynamics of the eruption and of the ejection and dispersal of the associated products. The problem is addressed through a fully interdisciplinary approach, involving volcanological field studies of selected 

eruptions, geochemical and petrological analyses of the hydrothermally altered rocks and, where present, of juvenile magma fragments, and the numerical modelling of explosion transport and depositional dynamics.
All the results obtained on the different studied eruptions will be propaedeutic for the generation of a reference, physically-based and numerically-tested model for the eruption dynamics of phreatic events to be applied to other case-studies and to be made available for the future production of hazard maps at specific volcanoes, so resulting in an important improvement of the present ability of the international volcanological community to face hazard assessment issues related to phreatic eruptions.

 

Participants:

 

Research Unit 1: UNIFI - Dip.to Scienze della Terra

  • Raffaello Cioni (Principal Investigator)
  • Zara Franceschini
  • Silvia Giansante

 

Research Unit 2: UNIPI - Dip.to Scienze della Terra

  • Marco Pistolesi (RU Responsible)
  • Anna Gioncada
  • Paolo Fulignati
  • Paola Marianelli
  • Marija Sergìïvna Voloschina

 

Research Unit 3: INGV - Sezione di Pisa

  • Mattia de Michieli Vitturi (RU Responsible)
  • Tomaso Esposti Ongaro
  • Augusto Neri

 

 

ACTIVITIES

 

RESULTS

 

 
ultimo aggiornamento: 31-Ago-2024
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