Recycled ejecta modulating Strombolian explosions

Capponi, Antonio and Taddeucci, Jacopo and Scarlato, Piergiorgio and Palladino, Danilo Mauro (2016) Recycled ejecta modulating Strombolian explosions. Bulletin of Volcanology, 78. ISSN 0258-8900

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Abstract

Two main end-members of eruptive regimes are identified from analyses of high-speed videos collected at Stromboli volcano (Italy), based on vent conditions: one where the vent is completely clogged by debris, and a second where the vent is open, without any cover. By detailing the vent processes for each regime, we provide the first account of how the presence of a cover affects eruptive dynamics compared to open-vent explosions. For clogged vents, explosion dynamics are controlled by the amount and grain size of the debris. Fine-grained covers are entirely removed by explosions, favouring the generation of fine ash plumes, while coarse-grained covers are only partially removed by the explosions, involving minor amounts of ash. In both fine- and coarse-grained cases, in-vent ground deformation of the debris reflect variations in the volumetric expansion of gas in the conduit, with rates of change of the deformation comparable to ground inflation related to pre-burst conduit pressurization. Eruptions involve the ejection of relatively slow and cold bombs and lapilli, and debris is observed to both fall back into the vent after each explosion and to gravitationally accumulate between explosions by rolling down the inner crater flanks to produce the cover itself. Part of this material may also contribute to the formation of a more degassed, crystallized and viscous magma layer at the top of the conduit. Conversely, open-vent explosions erupt with hotter pyroclasts, with higher exit velocity and with minor or no ash phase involved.

Item Type:
Journal Article
Journal or Publication Title:
Bulletin of Volcanology
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1900/1906
Subjects:
ID Code:
81039
Deposited By:
Deposited On:
18 Aug 2016 08:26
Refereed?:
Yes
Published?:
Published
Last Modified:
07 Apr 2020 04:04