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| Titel |
{Interpretation of intersismic deformations and the seismic cycle associated with large subduction earthquakes |
| VerfasserIn |
Olga Trubienko, Luce Fleitout, Jean-Didier Garaud |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051448
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| Zusammenfassung |
| The intersismic deformation of plates in the neighborhood of subduction zones generating
large earthquakes are most often modeled with the help of elastic backslip models.
However the very large and long post-sismic slip observed in areas around Sumatra or
in Chile clearly indicate a relaxation in the asthenosphere with viscosities of the
order of 1019 Pas. Using a 2D finite element model, we compare the deformations
during the seismic cycle predicted by a ’realistic’ model with an asthenosphere, plate
velocities imposed in the far-field and periodic earthquakes with the deformations
predicted from an elastic backslip model, a model with a blocked part of the subduction
zone and imposed ’far field’ plate velocities and models with viscoelastic backslip.
We find quite expectedly that the elastic model provides good predictions only in
the case where the viscosities are sufficiently high so that viscous relaxation is
negligible on the time-scale of the seismic cycle. In the model with imposed ’far
field’ plate velocities, the whole plates are progressively compressed and the results
strongly depend upon where exactly the velocities are applied. The ’viscoelastic
backslip’ and the ’realistic’ models yield very similar deformations through the
sismic cycle. In our view, only these last two models are appropriate to model the
intersismic deformations. We show that the nature of the viscoelastic rheology of the
asthenosphere (Burger versus Maxwell)) can be quantified from the relative amplitudes of
intersismic versus post-sismic deformations. Finally, we find that the details of the
mantle wedge area affect significantly the vertical motions away from the subduction
zone. |
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