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The Influence of Viscoelastic Crustal Rheologies on Volcanic Ground Deformation: Insights From Models of Pressure and Volume Change

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Original languageEnglish
Pages (from-to)8127-8146
Number of pages20
JournalJournal of Geophysical Research: Solid Earth
Volume124
Issue number8
Early online date31 Jul 2019
DOIs
DateAccepted/In press - 24 Jul 2019
DateE-pub ahead of print - 31 Jul 2019
DatePublished (current) - 19 Aug 2019

Abstract

Inelastic rheological behavior, such as viscoelasticity, is increasingly utilized in the modeling of volcanic ground deformation, as elevated thermal regimes induced by magmatic systems may necessitate the use of a mechanical model containing a component of time-dependent viscous behavior. For the modeling of a given amplitude and footprint of ground deformation, incorporating a viscoelastic regime has been shown to reduce the magma reservoir overpressure requirements suggested by elastic models. This phenomenon, however, is restricted to pressure-based analyses and the associated creep behavior. Viscoelastic materials exhibit additional constitutive time-dependent behaviors, determined by the stress and strain states, that are yet to be analyzed in the context of volcanic ground deformation. By utilizing a mechanically homogeneous model space and distinct reservoir evolutions, we provide a comparison of three viscoelastic rheological models, including the commonly implemented Maxwell and Standard Linear Solid configurations, and their time-dependent behaviors from a fundamental perspective. We also investigate the differences between deformation time series resulting from a pressurization or volume change, two contrasting approaches that are assumed to be equivalent through elastic modeling. Our results illustrate that the perceived influence of viscoelasticity is dependent on the mode of deformation, with stress-based pressurization models imparting enhanced deformation relative to the elastic models, thus reducing pressure requirements. Strain-based volumetric models, however, exhibit reduced levels of deformation and may produce episodes of apparent ground subsidence induced by source inflation or vice versa, due to the relaxation of crustal stresses, dependent on whether the reservoir is modeled to be expanding or contracting, respectively.

    Research areas

  • numerical modeling, rheology, unrest, viscoelasticity, volcanic deformation

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via American Geophysical Union at https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JB017832 . Please refer to any applicable terms of use of the publisher.

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