Publication Date:
2019-03-29
Description:
Solfatara crater is locatedwithin the Campi Flegrei caldera to the west of Naples (Italy). It is one of the largest fumarolic
manifestations known, and the rocks hosting the hydrothermal system are affected by intense hydrothermal
alteration. Alteration can result in changes of degassing behavior, and in the formation of a cap rock
thereby increasing the probability of phreatic eruptions. Here, we investigate the effects of alunitic (solfataric)
alteration on the mineralogy, the physical properties (porosity, density, permeability) and the mechanical properties
(strength) of the rocks involved, aswell as its influence on fragmentation and ejection behavior. Our results
showthat the pristine mineralogy of deposits fromthe vicinity of the Solfatara cryptodome and from Pisciarelli is
almost completely replaced by amorphous silica and alunite. The differences in the degree of alteration among
the samples series are reflected in the investigated properties and behavior aswell as in the analysis of the experimentally
generated particles. Alunitic alteration increases porosity and permeability,whereas it reduces density,
elastic wave velocity and strength leading to higher fragmentation and ejection speeds for the sample series
examined in this study. Our results also show that alteration results in the generation of a high fraction of fines
(particle sizes b10 μm) during fragmentation, mainly composed of alunite crystals. Due to their potential for inducing
chronic disease, dispersion of such material should represent a serious health hazard on a local scale and
the evaluation of precautions should be considered.
Description:
Published
Description:
128-143
Description:
3V. Proprietà dei magmi e dei prodotti vulcanici
Description:
JCR Journal
Keywords:
Solfataric alteration
;
Phreatic eruption
;
Fragmentation
;
Permeability
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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