Characteristics of viscoelastic crustal deformation following a megathrust earthquake: discrepancy between the apparent and intrinsic relaxation time constants
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- Fukahata, Yukitoshi
- Disaster Prevention Research Institute, Kyoto University
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- Matsu’ura, Mitsuhiro
- Institute of Statistical Mathematics, Tachikawa
Abstract
The viscoelastic deformation of an elastic–viscoelastic composite system is significantly different from that of a simple viscoelastic medium. Here, we show that complicated transient deformation due to viscoelastic stress relaxation after a megathrust earthquake can occur even in a very simple situation, in which an elastic surface layer (lithosphere) is underlain by a viscoelastic substratum (asthenosphere) under gravity. Although the overall decay rate of the system is controlled by the intrinsic relaxation time constant of the asthenosphere, the apparent decay time constant at each observation point is significantly different from place to place and generally much longer than the intrinsic relaxation time constant of the asthenosphere. It is also not rare that the sense of displacement rate is reversed during the viscoelastic relaxation. If we do not bear these points in mind, we may draw false conclusions from observed deformation data. Such complicated transient behavior can be explained mathematically from the characteristics of viscoelastic solution: for an elastic–viscoelastic layered half-space, the viscoelastic solution is expressed as superposition of three decaying components with different relaxation time constants that depend on wavelength.
Journal
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- Pure and Applied Geophysics
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Pure and Applied Geophysics 175 (2), 549-558, 2018-02
Springer Nature
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Details 詳細情報について
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- CRID
- 1050564288163967360
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- NII Article ID
- 120006591432
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- ISSN
- 00334553
- 14209136
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- HANDLE
- 2433/237393
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- Text Lang
- en
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- Article Type
- journal article
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- Data Source
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- IRDB
- Crossref
- CiNii Articles
- KAKEN