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Temperature-dependent viscoelastic modeling of ground deformation: Application to Etna volcano during the 1993–1997 inflation period
Language
English
Obiettivo Specifico
3.6. Fisica del vulcanismo
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
/172 (2009)
Publisher
Elsevier
Pages (printed)
299–309
Issued date
2009
Abstract
We used the Finite Element Method (FEM) for modeling time-dependent ground deformation due to
volcanic pressure sources embedded in a viscoelastic medium. Especially in volcanic areas, the presence
of heterogeneous materials and high temperatures produce a lower effective viscosity of the Earth’s
crust that calls for considering the thermal regime of crustal volume surrounding the magmatic sources.
We propose a thermo-mechanical numerical model for evaluating the temperature dependency of the
viscoelastic solution. Both temperature distributions and ground deformation are evaluated by solving
an axi-symmetric problem to estimate the effects of thermo-viscoelastic response of the medium. The
thermo-mechanical model permits to evidence that viscoelastic relaxation is responsible for significant
time-dependent variations in long-term deformation. These effects may be relevant for the interpretation
and quantitative assessments of the pressure changes within magmatic sources. With this in mind,
we reviewed the ground deformation observed on Etna volcano during the 1993–1997 inflation period
by setting up a fully 3D temperature-dependent viscoelastic model. Since 1993 different geodetic measurements
(EDM, GPS, SAR and leveling data) identified an inflationary phase characterized by a uniform
and continuous expansion of the overall volcano edifice that was not perturbed by eruptive activity.
The numerical model, including significant viscoelastic material and reduced crustal rigidity around the
magmatic source, enables to produce deformation comparable with those obtained from elastic model,
requiring a significantly lower pressure. For a purely elastic model with the same geometry and rigidity
the pressure change necessary to describe the 1993 through 1997 inflation is around 320MPa, whereas
for the viscoelastic model a pressure increase of about 200MPa is required.
volcanic pressure sources embedded in a viscoelastic medium. Especially in volcanic areas, the presence
of heterogeneous materials and high temperatures produce a lower effective viscosity of the Earth’s
crust that calls for considering the thermal regime of crustal volume surrounding the magmatic sources.
We propose a thermo-mechanical numerical model for evaluating the temperature dependency of the
viscoelastic solution. Both temperature distributions and ground deformation are evaluated by solving
an axi-symmetric problem to estimate the effects of thermo-viscoelastic response of the medium. The
thermo-mechanical model permits to evidence that viscoelastic relaxation is responsible for significant
time-dependent variations in long-term deformation. These effects may be relevant for the interpretation
and quantitative assessments of the pressure changes within magmatic sources. With this in mind,
we reviewed the ground deformation observed on Etna volcano during the 1993–1997 inflation period
by setting up a fully 3D temperature-dependent viscoelastic model. Since 1993 different geodetic measurements
(EDM, GPS, SAR and leveling data) identified an inflationary phase characterized by a uniform
and continuous expansion of the overall volcano edifice that was not perturbed by eruptive activity.
The numerical model, including significant viscoelastic material and reduced crustal rigidity around the
magmatic source, enables to produce deformation comparable with those obtained from elastic model,
requiring a significantly lower pressure. For a purely elastic model with the same geometry and rigidity
the pressure change necessary to describe the 1993 through 1997 inflation is around 320MPa, whereas
for the viscoelastic model a pressure increase of about 200MPa is required.
Type
article
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Del Negro et al PEPI 2009.pdf
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